xfsprogs: add cross-compile fix patch

Don't use CFLAGS (target) with BUILD_CC (host), fixes:
http://autobuild.buildroot.net/results/c94/c945bdb1427b55e03901027fa674b577e45963a1/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>