[compile-rt] Move stripping of signature from fault address to GetAddress()

[yln]

Summary

With the new header which takes care of the ptrauth #ifdef'ing, we can
now move the stripping of the ptrauth signature to it's natural place:
SignalContext::GetAddress() which is defined in the (non-Darwin
specific) file sanitizer_posix.cpp.

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp

292

this one is confusing without looking into the header
In followup patch, can you please replace ptrauth_strip with inline function internal_ptrauth_strip or SANITIZER_PTRAUTH_STRIP() macro?

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

 //===-- sanitizer_mac.cpp -------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
# elif defined(__i386__)
   *pc = ucontext->uc_mcontext->__ss.__eip;
   *bp = ucontext->uc_mcontext->__ss.__ebp;
   *sp = ucontext->uc_mcontext->__ss.__esp;
 # else
 # error "Unknown architecture"
 # endif
 }
 
-void SignalContext::InitPcSpBp() {
-  addr = (uptr)ptrauth_strip((void *)addr, 0);
-  GetPcSpBp(context, &pc, &sp, &bp);
-}
+void SignalContext::InitPcSpBp() { GetPcSpBp(context, &pc, &sp, &bp); }
 
 void InitializePlatformEarly() {
   // Only use xnu_fast_mmap when on x86_64 and the OS supports it.
   use_xnu_fast_mmap =
 #if defined(__x86_64__)
       GetMacosVersion() >= MACOS_VERSION_HIGH_SIERRA_DOT_RELEASE_4;
 #else
       false;

compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp

 //===-- sanitizer_posix.cpp -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is shared between AddressSanitizer and ThreadSanitizer
 // run-time libraries and implements POSIX-specific functions from
 // sanitizer_posix.h.
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_platform.h"
 
 #if SANITIZER_POSIX
 
 #include "sanitizer_common.h"
 #include "sanitizer_file.h"
 #include "sanitizer_flags.h"
 #include "sanitizer_libc.h"
 #include "sanitizer_posix.h"
 #include "sanitizer_procmaps.h"
+#include "sanitizer_ptrauth.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <sys/mman.h>
 
 #if SANITIZER_FREEBSD
 // The MAP_NORESERVE define has been removed in FreeBSD 11.x, and even before
 // that, it was never implemented.  So just define it to zero.
 #undef  MAP_NORESERVE
if (segment.IsExecutable() &&
       return true;
     }
   }
   return false;
 }
 
 uptr SignalContext::GetAddress() const {
   auto si = static_cast<const siginfo_t *>(siginfo);
-  return (uptr)si->si_addr;
+  return (uptr)ptrauth_strip(si->si_addr, 0);
 }
 
 bool SignalContext::IsMemoryAccess() const {
   auto si = static_cast<const siginfo_t *>(siginfo);
   return si->si_signo == SIGSEGV;
 }
 
 int SignalContext::GetType() const {