Bug 1485716 - part 1 - always use frame pointers on aarch64 windows; r=dmajor

This support is not necessary, but the ABI conventions
page (https://docs.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions)
encourages people to use frame pointers for fast stack walking, and
using frame pointers means we're compatible with ETW, which is a Good
Thing.

build/autoconf/frameptr.m4

@@ -30,13 +30,15 @@ AC_DEFUN([MOZ_SET_FRAMEPTR_FLAGS], [
   fi
 
   # If we are debugging, profiling, using sanitizers, or on win32 we want a
-  # frame pointer.
+  # frame pointer.  It is not required to enable frame pointers on AArch64
+  # Windows, but we enable it for compatibility with ETW.
   if test -z "$MOZ_OPTIMIZE" -o \
           -n "$MOZ_PROFILING" -o \
           -n "$MOZ_DEBUG" -o \
           -n "$MOZ_MSAN" -o \
           -n "$MOZ_ASAN" -o \
-          "$OS_ARCH:$CPU_ARCH" = "WINNT:x86"; then
+          "$OS_ARCH:$CPU_ARCH" = "WINNT:x86" -o \
+	  "$OS_ARCH:$CPU_ARCH" = "WINNT:aarch64"; then
     MOZ_FRAMEPTR_FLAGS="$MOZ_ENABLE_FRAME_PTR"
   else
     MOZ_FRAMEPTR_FLAGS="$MOZ_DISABLE_FRAME_PTR"