Build native coverage variant of APEXes when needed

When the native coverage is enabled, APEXes (and files there) are built
for native coverage as well.

Bug: 138952487
Test: make -j NATIVE_COVERAGE=true COVERAGE_PATHS='*' com.android.resolv
find out -name "*.gcno" | grep DnsResolver shows files

Test: libnetd_resolv.zip is found under
$(TARGET_OUT)/apex/com.android.resolv/lib directory

Change-Id: I97bcee9bf8ffc0dc71453abbdb613ed56ea2cdb4
diff --git a/cc/library.go b/cc/library.go
index b193ab7..f9698c4 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -814,6 +814,10 @@
 	return true
 }
 
+func (library *libraryDecorator) coverageOutputFilePath() android.OptionalPath {
+	return library.coverageOutputFile
+}
+
 func getRefAbiDumpFile(ctx ModuleContext, vndkVersion, fileName string) android.Path {
 	isLlndkOrNdk := inList(ctx.baseModuleName(), *llndkLibraries(ctx.Config())) || inList(ctx.baseModuleName(), ndkMigratedLibs)