Allow actually passing CXXFLAGS into external/libnumbertext

...as external/libnumbertext/ExternalProject_libnumbertext.mk tried to do

Change-Id: I8c0deeaa1db31fc0ab5042c7f8a1ced0d65e29ee
Reviewed-on: https://gerrit.libreoffice.org/53806Reviewed-by: László Németh <nemeth@numbertext.org>
Tested-by: Jenkins <ci@libreoffice.org>

external/libnumbertext/UnpackedTarball_libnumbertext.mk

@@ -13,4 +13,10 @@ $(eval $(call gb_UnpackedTarball_set_tarball,libnumbertext,$(LIBNUMBERTEXT_TARBA
 
 $(eval $(call gb_UnpackedTarball_update_autoconf_configs,libnumbertext))
 
+$(eval $(call gb_UnpackedTarball_set_patchlevel,libnumbertext,0))
+
+$(eval $(call gb_UnpackedTarball_add_patches,libnumbertext, \
+    external/libnumbertext/configure.patch \
+))
+
 # vim: set noet sw=4 ts=4:

external/libnumbertext/configure.patch

+--- configure.ac
++++ configure.ac
+@@ -22,7 +22,6 @@
+ 
+ dnl Checks for typedefs, structures, and compiler characteristics.
+ AC_LANG([C++])
+-CXXFLAGS='-Wall -std=c++11'
+ 
+ AC_CHECK_HEADERS([codecvt regex])
+