configure: Fix check for libunbound to require v1.5.0 as minimum.

Versions of libunbound before v1.4.21 do not compile with Asterisk.
However, since v1.4.21 has a configure script bug that fails to detect the
ldns library (which is fixed in v1.4.22) and v1.4.22 is not an easily
detectable version we will require v1.5.0 as a minimum version of the
library to work with Asterisk.

ASTERISK-25108 #close
Reported by: Richard Mudgett

Change-Id: Ieb228bfb01467573fc121c7356a9dde27128894d

configure

@@ -22968,6 +22968,13 @@ fi
+# libunbound v1.5.0 added the ub_ctx_add_ta_autr() API call that we can
+# detect as a useable version so that is going to be the minimum version
+# that we will require.
+# Technically v1.4.21 and later could be used but v1.4.21 has a configure
+# script bug which does not find the ldns library.  The bug is fixed in
+# v1.4.22 but that version is not easily detectable.
+#
 if test "x${PBX_UNBOUND}" != "x1" -a "${USE_UNBOUND}" != "no"; then
    pbxlibdir=""
@@ -22979,7 +22986,7 @@ if test "x${PBX_UNBOUND}" != "x1" -a "${USE_UNBOUND}" != "no"; then
          pbxlibdir="-L${UNBOUND_DIR}"
       fi
    fi
-   pbxfuncname="ub_ctx_create"
+   pbxfuncname="ub_ctx_add_ta_autr"
    if test "x${pbxfuncname}" = "x" ; then   # empty lib, assume only headers
       AST_UNBOUND_FOUND=yes
    else

configure.ac

@@ -2006,7 +2006,14 @@ AST_EXT_TOOL_CHECK([NETSNMP], [net-snmp-config], , [--agent-libs],
 
 AST_EXT_LIB_CHECK([NEWT], [newt], [newtBell], [newt.h])
 
-AST_EXT_LIB_CHECK([UNBOUND], [unbound], [ub_ctx_create], [unbound.h], [])
+# libunbound v1.5.0 added the ub_ctx_add_ta_autr() API call that we can
+# detect as a useable version so that is going to be the minimum version
+# that we will require.
+# Technically v1.4.21 and later could be used but v1.4.21 has a configure
+# script bug which does not find the ldns library.  The bug is fixed in
+# v1.4.22 but that version is not easily detectable.
+#
+AST_EXT_LIB_CHECK([UNBOUND], [unbound], [ub_ctx_add_ta_autr], [unbound.h], [])
 
 AST_EXT_LIB_CHECK([UNIXODBC], [odbc], [SQLConnect], [sql.h], [])