Move clang warnings override out of libgui

These clang warnings overrides were introduced to mute warnings brought
in from bufferhub and its dependencies. A better way to handle this is
to mute those warnings in BufferHub headers and keep libgui free from
those overrides.

Bug: 72172820
Test: Build system
Change-Id: I7d8aa233ceeef353a7db2c43431ae64360c668b1
diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 065d44d..6655eb6 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -65,6 +65,9 @@
         // Allow implicit instantiation for templated class function
         "-Wno-undefined-func-template",
 
+        // Allow explicitly marking struct as packed even when unnecessary
+        "-Wno-packed",
+
         "-DDEBUG_ONLY_CODE=0",
     ],