symbols in stub library isn't affected by -fvisibility=hidden

Fixing the bug that -fvisibility=hidden in a cc_library is used even
when compiling stub.c file where the symbols shouldn't be hidden.

Bug: 144781653
Test: add folowing to libEGL and build
+    stubs: {
+        symbol_file: "libEGL.map.txt",
+        versions: ["29"],
+    },

Change-Id: Iab70f36a4fb98737fc35827dbc9e1ca1a99d4354