Add thread safety check to libgui build

Fix places that had errors to ensure locks are correctly held in libgui

Test: Builds
Bug: 268091723
Change-Id: I8a94edeb649608ff66d25a482026a81074466305
diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 6c9c28a..21900a0 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -254,6 +254,10 @@
     lto: {
         thin: true,
     },
+
+    cflags: [
+        "-Wthread-safety",
+    ],
 }
 
 // Used by media codec services exclusively as a static lib for