package/pugixml: Fix CMakelists.txt cxx_long_long_type bug.
CMakelist.txt tries to enable the cxx_long_long_type option,
even if the feature isn't available. (Which causes some builds to fail)
The included patch checks if the option is present before applying it.
The patch was backported from:
https://github.com/zeux/pugixml/commit/
4dbb5646196a4a3cc94097f1473ef11d1d44df11
Signed-off-by: Theo Debrouwere <t.debrouwere@televic.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>