x11/libxcb: Update to 1.14

Update x11/libxcb to 1.14.
Clean up the makefile:

• Remove the dependency on check and libxslt, they are only needed for tests which aren't built and installed anyway.
• No need to use gmake
• Correct configure options
• Have libxcb use pkgconfig to figure out cflags and ldflags, instead of hardcoding some cflags and ldflags in the Makefile.