Conditionally apply rustdoc flags to third party crates

This CL changes the logic in rust/builder.go so that some rustdoc flags
are only applied to external crates.  This will allow us to since
warnings and deal with soft-failures in external crates while allowing
us to be more strict with our internal Rust code.

Bug: 195136952
Test: m rustdoc
Change-Id: Icdde304bbbb323cae9657e8f842f58ae79e811ce

cc/compiler.go

@@ -450,7 +450,7 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 		"${config.CommonGlobalCflags}",
 		fmt.Sprintf("${config.%sGlobalCflags}", hod))
 
-	if isThirdParty(modulePath) {
+	if android.IsThirdPartyPath(modulePath) {
 		flags.Global.CommonFlags = append(flags.Global.CommonFlags, "${config.ExternalCflags}")
 	}
 
@@ -675,28 +675,6 @@ func compileObjs(ctx android.ModuleContext, flags builderFlags,
 	return transformSourceToObj(ctx, subdir, srcFiles, flags, pathDeps, cFlagsDeps)
 }
 
-var thirdPartyDirPrefixExceptions = []*regexp.Regexp{
-	regexp.MustCompile("^vendor/[^/]*google[^/]*/"),
-	regexp.MustCompile("^hardware/google/"),
-	regexp.MustCompile("^hardware/interfaces/"),
-	regexp.MustCompile("^hardware/libhardware[^/]*/"),
-	regexp.MustCompile("^hardware/ril/"),
-}
-
-func isThirdParty(path string) bool {
-	thirdPartyDirPrefixes := []string{"external/", "vendor/", "hardware/"}
-
-	if android.HasAnyPrefix(path, thirdPartyDirPrefixes) {
-		for _, prefix := range thirdPartyDirPrefixExceptions {
-			if prefix.MatchString(path) {
-				return false
-			}
-		}
-		return true
-	}
-	return false
-}
-
 // Properties for rust_bindgen related to generating rust bindings.
 // This exists here so these properties can be included in a cc_default
 // which can be used in both cc and rust modules.