configure: Fix HAVE_PJSIP_EVSUB_GRP_LOCK not set with external pjproject

There was a typo in configure.ac preventing HAVE_PJSIP_EVSUB_GRP_LOCK
from getting set when using an external pjproject.

ASTERISK-26099 #close
Reported-by: Ross Beer

Change-Id: I709af70428e125fb5ccd44b171d25dd29141f0ae

configure

@@ -25199,7 +25199,7 @@ if test "x${PBX_PJSIP_EVSUB_GRP_LOCK}" != "x1" -a "${USE_PJSIP_EVSUB_GRP_LOCK}"
          pbxlibdir="-L${PJSIP_EVSUB_GRP_LOCK_DIR}"
       fi
    fi
-   pbxfuncname="pjsip_evsub_add_lock"
+   pbxfuncname="pjsip_evsub_add_ref"
    if test "x${pbxfuncname}" = "x" ; then   # empty lib, assume only headers
       AST_PJSIP_EVSUB_GRP_LOCK_FOUND=yes
    else

configure.ac

@@ -2196,7 +2196,7 @@ if test "$USE_PJPROJECT" != "no" ; then
       LIBS="${saved_libs}"
       CPPFLAGS="${saved_cppflags}"
 
-      AST_EXT_LIB_CHECK([PJSIP_EVSUB_GRP_LOCK], [pjsip], [pjsip_evsub_add_lock], [pjsip.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
+      AST_EXT_LIB_CHECK([PJSIP_EVSUB_GRP_LOCK], [pjsip], [pjsip_evsub_add_ref], [pjsip.h], [$PJPROJECT_LIB], [$PJPROJECT_CFLAGS])
    fi
 fi