Fix aarch64 setjmp abi

We now store values in jmp_buf where the compiler wants them to be. This
fixes code that calls __builtin_setjmp() and __builtin_longjmp() such as
libunwind. All libcxxabi tests are now passing on ARM64.

See #1076

build/htags

@@ -66,7 +66,7 @@ set -- --regex-c='/^extern [^(]*(\*const \([^)]*\))(/\1/b' "$@"
 #   struct WorstSoftwareEver;
 set -- --regex-c='/^struct.*;$/uehocruehcroue/b' "$@"
 
-exec $TAGS                                                        \
+build/run $TAGS                                                   \
      -e                                                           \
      --langmap=c:.c.h                                             \
      --exclude=libc/nt/struct/imagefileheader.internal.h          \

build/run

@@ -1,9 +1,8 @@
 #!/bin/sh
-if printf '%s\n' "$*" | grep aarch64 >/dev/null 2>&1; then
-  if [ ! -f o/third_party/qemu/qemu-aarch64 ]; then
-    make -j8 o/third_party/qemu/qemu-aarch64
-  fi
-  exec o/third_party/qemu/qemu-aarch64 "$@"
+UNAMEM=$(uname -m)
+UNAMES=$(uname -s)
+if [ x"$UNAMES" = x"Darwin" ] && [ x"$UNAMEM" = x"arm64" ]; then
+  exec ape "$@"
 else
   exec "$@"
 fi