Prevent potential issues mixing system/non-system libwps and libnumbertext

Change-Id: I1e47b3cc01df3d204ef7ef36f2432830aa18e65e
Reviewed-on: https://gerrit.libreoffice.org/53978Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>

configure.ac

@@ -3813,6 +3813,21 @@ if test -n "$enable_dbgutil" -a "$enable_dbgutil" != "no"; then
     else
         with_system_gpgmepp=no
     fi
+    # As mixing system libwps and non-system libnumbertext or vice versa likely causes trouble (see
+    # 603074c5f2b84de8a24593faf807da784b040625 "Pass _GLIBCXX_DEBUG into external/libwps" and the
+    # mail thread starting at <https://gcc.gnu.org/ml/gcc/2018-05/msg00057.html> "libstdc++: ODR
+    # violation when using std::regex with and without -D_GLIBCXX_DEBUG"), simply make sure neither
+    # of those two is using the system variant:
+    if test "$with_system_libnumbertext" = "yes"; then
+        AC_MSG_ERROR([--with-system-libnumbertext conflicts with --enable-dbgutil])
+    else
+        with_system_libnumbertext=no
+    fi
+    if test "$with_system_libwps" = "yes"; then
+        AC_MSG_ERROR([--with-system-libwps conflicts with --enable-dbgutil])
+    else
+        with_system_libwps=no
+    fi
 else
     ENABLE_DBGUTIL=""
     MSVC_USE_DEBUG_RUNTIME=""