Make GetTargetProperties() aware of more complex targets, like 'android_arm', instead of just 'android'.

Test: Added new unit test and updated existing tests.

Test: bazel build //bionic/... //external/... //frameworks/... //system/...

Test: ./build/bazel/scripts/run_presubmits.sh

Change-Id: I250d1964f5cf42b92ddb929379d35d8c844423f7
diff --git a/bp2build/build_conversion.go b/bp2build/build_conversion.go
index 7a73e18..388c8cf 100644
--- a/bp2build/build_conversion.go
+++ b/bp2build/build_conversion.go
@@ -568,6 +568,9 @@
 			return true
 		}
 	default:
+		if !value.IsValid() {
+			return true
+		}
 		zeroValue := reflect.Zero(value.Type())
 		result := value.Interface() == zeroValue.Interface()
 		return result