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
diff --git a/Android.mk b/Android.mk
index 0f53ed9..c451ef4 100644
--- a/Android.mk
+++ b/Android.mk
@@ -18,6 +18,7 @@
   -D_BSD_SOURCE \
   -D_FILE_OFFSET_BITS=64 \
   -D_LARGEFILE_SOURCE \
+  -include sys/sysmacros.h \
   -Wall -Werror -Wno-sign-compare \
 
 # Build the shared library.