BuildSystem: For consistency, avoid double-checking via if clauses.

In the script ./configure, AST_EXT_LIB_CHECK and AST_PKG_CONFIG_CHECK first test
whether parameter 1 was already found. Consequently, an if-test on PBX_ just a
line below is redundant, if exactly the same parameter 1 is used again.

No performance gain is expected by this change. However, because this strategy
is used all over in ./configure except for two places, this change aims to
create more consistency: Only do something different if there is a reason to do
so.

Change-Id: I4a6f48127b7af3a48168c917e888be1f70625027

configure

@@ -19762,9 +19762,7 @@ _ACEOF
 fi
-
-if test "${PBX_BFD}" = "0"; then
-  # Fedora/RedHat/CentOS require extra libraries
+# Fedora/RedHat/CentOS require extra libraries
 if test "x${PBX_BFD}" != "x1" -a "${USE_BFD}" != "no"; then
    pbxlibdir=""
@@ -19779,9 +19777,9 @@ if test "x${PBX_BFD}" != "x1" -a "${USE_BFD}" != "no"; then
       ast_ext_lib_check_save_CFLAGS="${CFLAGS}"
       CFLAGS="${CFLAGS} "
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for bfd_check_format in -lbfd" >&5
-$as_echo_n "checking for bfd_check_format in -lbfd... " >&6; }
-if ${ac_cv_lib_bfd_bfd_check_format+:} false; then :
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for bfd_openr in -lbfd" >&5
+$as_echo_n "checking for bfd_openr in -lbfd... " >&6; }
+if ${ac_cv_lib_bfd_bfd_openr+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
@@ -19795,27 +19793,27 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char bfd_check_format ();
+char bfd_openr ();
 int
 main ()
 {
-return bfd_check_format ();
+return bfd_openr ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_bfd_bfd_check_format=yes
+  ac_cv_lib_bfd_bfd_openr=yes
 else
-  ac_cv_lib_bfd_bfd_check_format=no
+  ac_cv_lib_bfd_bfd_openr=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_bfd_bfd_check_format" >&5
-$as_echo "$ac_cv_lib_bfd_bfd_check_format" >&6; }
-if test "x$ac_cv_lib_bfd_bfd_check_format" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_bfd_bfd_openr" >&5
+$as_echo "$ac_cv_lib_bfd_bfd_openr" >&6; }
+if test "x$ac_cv_lib_bfd_bfd_openr" = xyes; then :
   AST_BFD_FOUND=yes
 else
   AST_BFD_FOUND=no
@@ -19861,10 +19859,7 @@ _ACEOF
 fi
-fi
-
-if test "${PBX_BFD}" = "0"; then
-  # openSUSE requires -lz
+# openSUSE requires -lz
 if test "x${PBX_BFD}" != "x1" -a "${USE_BFD}" != "no"; then
    pbxlibdir=""
@@ -19879,9 +19874,9 @@ if test "x${PBX_BFD}" != "x1" -a "${USE_BFD}" != "no"; then
       ast_ext_lib_check_save_CFLAGS="${CFLAGS}"
       CFLAGS="${CFLAGS} "
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for bfd_check_format in -lbfd" >&5
-$as_echo_n "checking for bfd_check_format in -lbfd... " >&6; }
-if ${ac_cv_lib_bfd_bfd_check_format+:} false; then :
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for bfd_openr in -lbfd" >&5
+$as_echo_n "checking for bfd_openr in -lbfd... " >&6; }
+if ${ac_cv_lib_bfd_bfd_openr+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
@@ -19895,27 +19890,27 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char bfd_check_format ();
+char bfd_openr ();
 int
 main ()
 {
-return bfd_check_format ();
+return bfd_openr ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_bfd_bfd_check_format=yes
+  ac_cv_lib_bfd_bfd_openr=yes
 else
-  ac_cv_lib_bfd_bfd_check_format=no
+  ac_cv_lib_bfd_bfd_openr=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_bfd_bfd_check_format" >&5
-$as_echo "$ac_cv_lib_bfd_bfd_check_format" >&6; }
-if test "x$ac_cv_lib_bfd_bfd_check_format" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_bfd_bfd_openr" >&5
+$as_echo "$ac_cv_lib_bfd_bfd_openr" >&6; }
+if test "x$ac_cv_lib_bfd_bfd_openr" = xyes; then :
   AST_BFD_FOUND=yes
 else
   AST_BFD_FOUND=no
@@ -19961,7 +19956,6 @@ _ACEOF
 fi
-fi
 case "${OSARCH}" in
 linux*)
@@ -20768,8 +20762,7 @@ $as_echo "#define HAVE_LIBEDIT 1" >>confdefs.h
 fi
    fi
-if test "${PBX_LIBEDIT}" != 1; then
-	# some platforms do not list libedit via pkg-config, for example OpenBSD 6.2
+# some platforms do not list libedit via pkg-config, for example OpenBSD 6.2
 if test "x${PBX_LIBEDIT}" != "x1" -a "${USE_LIBEDIT}" != "no"; then
    pbxlibdir=""
@@ -20866,7 +20859,6 @@ _ACEOF
 fi
-fi
 if test "${PBX_LIBEDIT}" != 1; then
 	as_fn_error $? "*** Please install the 'libedit' development package." "$LINENO" 5
 	exit 1

configure.ac

@@ -1458,16 +1458,10 @@ PKG_PROG_PKG_CONFIG()
 AST_EXT_LIB_CHECK([ALSA], [asound], [snd_spcm_init], [alsa/asoundlib.h], [-lm -ldl])
 
 AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_openr], [bfd.h])
-
-if test "${PBX_BFD}" = "0"; then
-  # Fedora/RedHat/CentOS require extra libraries
-  AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_check_format], [bfd.h], [-ldl -liberty])
-fi
-
-if test "${PBX_BFD}" = "0"; then
-  # openSUSE requires -lz
-  AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_check_format], [bfd.h], [-ldl -liberty -lz])
-fi
+# Fedora/RedHat/CentOS require extra libraries
+AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_openr], [bfd.h], [-ldl -liberty])
+# openSUSE requires -lz
+AST_EXT_LIB_CHECK([BFD], [bfd], [bfd_openr], [bfd.h], [-ldl -liberty -lz])
 
 case "${OSARCH}" in
 linux*)
@@ -1575,10 +1569,8 @@ if test "${USE_ILBC}" != "no"; then
 fi
 
 AST_PKG_CONFIG_CHECK(LIBEDIT, libedit)
-if test "${PBX_LIBEDIT}" != 1; then
-	# some platforms do not list libedit via pkg-config, for example OpenBSD 6.2
-	AST_EXT_LIB_CHECK([LIBEDIT], [edit], [history_init], [histedit.h], [-ltermcap])
-fi
+# some platforms do not list libedit via pkg-config, for example OpenBSD 6.2
+AST_EXT_LIB_CHECK([LIBEDIT], [edit], [history_init], [histedit.h], [-ltermcap])
 if test "${PBX_LIBEDIT}" != 1; then
 	AC_MSG_ERROR(*** Please install the 'libedit' development package.)
 	exit 1