Cope with <sys/sysmacros.h> no longer being included by <sys/types.h>.

I'm not sure where (if anywhere) is upstream here, so modifying our makefile
rather than the source.

Bug: https://github.com/android-ndk/ndk/issues/398
Test: builds
Change-Id: I2690bbba6c4ac98c957f780e9b9625e8690052f8