Android: also ignore the libs left on the root.

Although, I don't really see why they are put here, outside the build dir.

.gitignore

@@ -8,6 +8,8 @@ Source/Core/Common/scmrev.h
 /[Bb]uild*/
 /[Bb]inary/
 /obj/
+# Android cmake builds to here then copies to Source/Android.
+/libs/
 # Ignore various files created by visual studio/msbuild
 *.ipch
 *.opensdf