gn-build: Get //utils:utils to compile

This CL conditionally removes the dependency on libcutils to get the
//utils:utils static library target to compile in GN. This technically breaks
the functionality on non-Android platforms until we come up with a common way to
make the logic work.

BUG=21339022

Change-Id: I47cd8f7991942dbe43a577cef1f95626560f7f72
1 file changed