Revert "Keep _FORTIFY_SOURCE=2 for libvulkan when enabling _FORT..."

Revert submission 3391212-_FORTIFY_SOURCE=3

Reason for revert: DroidMonitor: Potential culprit for http://b/383164857 - verifying through ABTD before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.

Reverted changes: /q/submissionid:3391212-_FORTIFY_SOURCE%3D3

Change-Id: I3682429d089d1c26b5ed74d7764ec4a3a447829b

Author: Liana Kazanova

vulkan/libvulkan/Android.bp

@@ -59,11 +59,6 @@ cc_library_shared {
         "-fstandalone-debug",
 
         //"-DLOG_NDEBUG=0",
-
-        // Keep -D_FORTIFY_SOURCE=2 in libvulkan.
-        // See b/291762537
-        "-U_FORTIFY_SOURCE",
-        "-D_FORTIFY_SOURCE=2",
     ],
 
     cppflags: [