The gtk/native/Makefile.am has set: CC = @CC_FOR_BUILD@ It shoudl also set: CFLAGS = @CFLAGS_FOR_BUILD@ Otherwise there might be build failures when doing cross build, for example, several CFLAGS are special to arm or mips, and the native gcc can't recognize them. The similar to CPPFLAGS and LDFLAGS.
Merged into master: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=fee85f01bb1d8b2019fea17afba36ad1846c42a7