Add LLNDK support for the VNDK

Instead of using the NDK headers and libraries, add LL-NDK specific
headers and library stubs for VNDK users. This allows us to provide an
expanded liblog interface.

Test: aosp_arm; m -j
Test: Enable BOARD_VNDK_VERSION on aosp_arm; m -j
Test: Inspect out/soong/build.ninja before/after (w/o vndk)
Change-Id: Ic85f07fa10c695b5baab10c41f5e0ad38700bf3d

cc/androidmk.go

@@ -298,3 +298,19 @@ func (c *stubDecorator) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkDa
 		return nil
 	})
 }
+
+func (c *llndkStubDecorator) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
+	ret.Class = "SHARED_LIBRARIES"
+
+	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) error {
+		c.libraryDecorator.androidMkWriteExportedFlags(w)
+
+		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+outputFile.Ext())
+		fmt.Fprintln(w, "LOCAL_STRIP_MODULE := false")
+		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
+		fmt.Fprintln(w, "LOCAL_UNINSTALLABLE_MODULE := true")
+		fmt.Fprintln(w, "LOCAL_NO_NOTICE_FILE := true")
+
+		return nil
+	})
+}