BuildSystem: Detect ca_list_path capabilities in external PJProject.

Since Asterisk 13.8, pj_ssl_cert_load_from_files2 got detected only in the
bundled PJProject but not in an external PJProject. Therefore, ca_list_path
could not be used in pjsip.conf. With this change, pj_ssl_cert_load_from_files2
is detected again to enable ca_list_path again.

ASTERISK-26303 #close

Change-Id: I4a4a0cdc5cdff33730911fb4cfc0498c069043d0

configure

@@ -25697,7 +25697,7 @@ if test "x${PBX_PJ_SSL_CERT_LOAD_FROM_FILES2}" != "x1" -a "${USE_PJ_SSL_CERT_LOA
          pbxlibdir="-L${PJ_SSL_CERT_LOAD_FROM_FILES2_DIR}"
       fi
    fi
-   pbxfuncname="pjsip/include/pjsip/sip_util.h"
+   pbxfuncname="pj_ssl_cert_load_from_files2"
    if test "x${pbxfuncname}" = "x" ; then   # empty lib, assume only headers
       AST_PJ_SSL_CERT_LOAD_FROM_FILES2_FOUND=yes
    else

configure.ac

@@ -2197,7 +2197,7 @@ if test "$USE_PJPROJECT" != "no" ; then
       CPPFLAGS="${saved_cppflags}"
 
       AST_EXT_LIB_CHECK([PJSIP_GET_DEST_INFO], [pjsip], [pjsip_get_dest_info], [pjsip.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
-      AST_EXT_LIB_CHECK([PJ_SSL_CERT_LOAD_FROM_FILES2], [pj], [pjsip/include/pjsip/sip_util.h], [pjlib.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
+      AST_EXT_LIB_CHECK([PJ_SSL_CERT_LOAD_FROM_FILES2], [pj], [pj_ssl_cert_load_from_files2], [pjlib.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
       AST_EXT_LIB_CHECK([PJSIP_EXTERNAL_RESOLVER], [pjsip], [pjsip_endpt_set_ext_resolver], [pjsip.h], [$PJPROJECT_LIBS], [$PJPROJECT_CFLAGS])
 
       saved_cppflags="${CPPFLAGS}"