Revert "Disable pointer authentication in app processes."

Revert "Disable pointer authentication in app processes."

Revert "[automerged blank] Disable pointer authentication in app..."

Revert submission 16712509-sc-dev-I3030c47be9d02a27505bd4775c1982a20755758c-sc-v2-dev

Reason for revert: PAC has shipped with S, and we're going with app compat outreach rather than regressing security.
Reverted Changes:
I3030c47be:Disable pointer authentication in app processes.
I3030c47be:Disable pointer authentication in app processes.
I84a696428:[automerged blank] Disable pointer authentication ...
Ibc52deaf3:[automerged blank] Disable pointer authentication ...

Change-Id: I7ebdfce99ef6387415eb21cd216344b8eaf64b61

cmds/app_process/Android.bp

@@ -64,8 +64,6 @@ cc_binary {
         "libwilhelm",
     ],
 
-    header_libs: ["bionic_libc_platform_headers"],
-
     compile_multilib: "both",
 
     cflags: [

cmds/app_process/app_main.cpp

@@ -15,7 +15,6 @@
 
 #include <android-base/macros.h>
 #include <binder/IPCThreadState.h>
-#include <bionic/pac.h>
 #include <hwbinder/IPCThreadState.h>
 #include <utils/Log.h>
 #include <cutils/memory.h>
@@ -183,10 +182,6 @@ int main(int argc, char* const argv[])
       ALOGV("app_process main with argv: %s", argv_String.string());
     }
 
-    // Because of applications that are using PAC instructions incorrectly, PAC
-    // is disabled in application processes for now.
-    ScopedDisablePAC x;
-
     AppRuntime runtime(argv[0], computeArgBlockSize(argc, argv));
     // Process command line arguments
     // ignore argv[0]