Add conditional PGO configuration for Zen Browser in macos mozconfig

configs/macos/mozconfig

@@ -6,7 +6,14 @@ ac_add_options --enable-eme=widevine
 export MOZ_MACBUNDLE_ID=${appId}
 export MOZ_MACBUNDLE_NAME="Zen Browser.app"
 
-
+if test "$ZEN_RELEASE"; then
+  if test "$ZEN_GA_DISABLE_PGO"; then
+    export ZEN_DUMMY=1
+  else
+    export MOZ_PGO=1
+    ac_add_options MOZ_PGO=1
+  fi
+fi
 
 if test "$SURFER_COMPAT" = "x86_64"; then
     ac_add_options --target=x86_64-apple-darwin