Store ninja file deps from PackageVarContext in the config

Store ninja file deps from ExistentPathForSource on a
PackageVarContext in the config instead of the PackageContext, as
the PackageContext may be shared between multiple tests running
in parallel.

Test: all soong tests
Change-Id: Ib1809a4dd4a82696e0fe48a87eac21a44684ecb5

android/package_ctx.go

@@ -56,7 +56,7 @@ func (e *configErrorWrapper) Errorf(format string, args ...interface{}) {
 	e.errors = append(e.errors, fmt.Errorf(format, args...))
 }
 func (e *configErrorWrapper) AddNinjaFileDeps(deps ...string) {
-	e.pctx.AddNinjaFileDeps(deps...)
+	e.config.addNinjaFileDeps(deps...)
 }
 
 type PackageVarContext interface {