Clean up the architecture-specific makefiles.

Group things appropriately and name each group.

Change-Id: I0da45eb0ccde19c31d5e984d0e6eb3dad26630dc
diff --git a/libc/Android.mk b/libc/Android.mk
index a81b6c2..56e9876 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -712,6 +712,7 @@
 LOCAL_SYSTEM_SHARED_LIBRARIES :=
 
 $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
+$(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_freebsd_src_files))
 include $(BUILD_STATIC_LIBRARY)
 
 
@@ -780,6 +781,7 @@
 LOCAL_SYSTEM_SHARED_LIBRARIES :=
 
 $(eval $(call patch-up-arch-specific-flags,LOCAL_CFLAGS,libc_common_cflags))
+$(eval $(call patch-up-arch-specific-flags,LOCAL_SRC_FILES,libc_openbsd_src_files))
 include $(BUILD_STATIC_LIBRARY)