BuildSystem: Avoid obsolete warning with HELP_STRING on autoconf.

Some configure scripts used both AC_HELP_STRING and its replacement
AS_HELP_STRING. For consistency and to avoid obsolete warnings, those were
changed to AS_HELP_STRING.

ASTERISK-26046

Change-Id: I8aad4fd2bdee40aa2a31ce3339a1eb33ff4f5b0f

autoconf/ast_ext_lib.m4

@@ -11,7 +11,7 @@ AC_DEFUN([AST_EXT_LIB_SETUP],
     $1_DESCRIP="$2"
     $1_OPTION="$3"
     PBX_$1=0
-    AC_ARG_WITH([$3], AC_HELP_STRING([--with-$3=PATH],[use $2 files in PATH$4]),
+    AC_ARG_WITH([$3], AS_HELP_STRING([--with-$3=PATH],[use $2 files in PATH$4]),
     [
 	case ${withval} in
 	n|no)

autoconf/ast_prog_ld.m4

@@ -3,7 +3,7 @@
 # find the pathname to the GNU or non-GNU linker
 AC_DEFUN([AST_PROG_LD],
 [AC_ARG_WITH([gnu-ld],
-    [AC_HELP_STRING([--with-gnu-ld],
+    [AS_HELP_STRING([--with-gnu-ld],
 	[assume the C compiler uses GNU ld @<:@default=no@:>@])],
     [test "$withval" = no || with_gnu_ld=yes],
     [with_gnu_ld=no])

configure.ac

@@ -1230,7 +1230,7 @@ AC_SUBST(AST_NATIVE_ARCH)
 
 dnl Check to see if rpath should be set in LDFLAGS
 AC_ARG_ENABLE(rpath,
-	[AC_HELP_STRING([--disable-rpath],
+	[AS_HELP_STRING([--disable-rpath],
 			[Disables rpath linker option checking])],
 	[case "${enableval}" in
 		y|ye|yes) check_rpath=yes ;;