Allow building Python on Mac with GNU xargs

GNU xargs executes the command at least once even if the standard input
is empty, unlike BSD xargs, which causes rm -r to be called with no
arguments ween the find command finds nothing leading to an error.
Adding -f to rm allows buikding with either implementation.

Change-Id: I0df5fcb379d2a5a8b1121594ec1a82d917d80dfc
Reviewed-on: https://gerrit.libreoffice.org/16116Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: David Tardon <dtardon@redhat.com>

external/python3/UnpackedTarball_python3.mk

@@ -31,6 +31,7 @@ $(eval $(call gb_UnpackedTarball_add_patches,python3,\
 	external/python3/python-3.3.3-msvc2012-winxp.patch.1 \
 	external/python3/python-3.3.5-pyexpat-symbols.patch.1 \
 	external/python3/python-3.3.5-vs2013.patch.1 \
+	external/python3/python-3.3.5-darwin-gnu-xargs.patch.1 \
 	external/python3/python-msvc-disable-sse2.patch.1 \
 	external/python3/python-lsan.patch.0 \
 	external/python3/ubsan.patch.0 \

external/python3/python-3.3.5-darwin-gnu-xargs.patch.1

+diff -ur python3.org/Mac/PythonLauncher/Makefile.in python3/Mac/PythonLauncher/Makefile.in
+--- python3.org/Mac/PythonLauncher/Makefile.in	2015-06-06 08:47:38.000000000 +0300
++++ python3/Mac/PythonLauncher/Makefile.in	2015-06-06 08:48:18.000000000 +0300
+@@ -53,7 +53,7 @@
+ 		--resource=$(srcdir)/factorySettings.plist \
+ 		--plist Info.plist \
+ 		build
+-	find "Python Launcher.app" -name '.svn' -print0 | xargs -0 rm -r
++	find "Python Launcher.app" -name '.svn' -print0 | xargs -0 rm -rf
+ 		
+ 
+ FileSettings.o: $(srcdir)/FileSettings.m