PAC/BTI: no need to keep using `hint`.

The toolchain is new enough that should be able to use the actual
instructions now...

Test: treehugger
Change-Id: I30aafcdc5386268344c40dc6cc9a22caf591915a

libc/arch-arm64/bionic/setjmp.S

@@ -118,7 +118,7 @@ END(_setjmp)
 // int sigsetjmp(sigjmp_buf env, int save_signal_mask);
 ENTRY(sigsetjmp)
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(sigsetjmp)
-  hint #25 // paciasp
+  paciasp
   .cfi_negate_ra_state
   stp x0, x30, [sp, #-16]!
   .cfi_def_cfa_offset 16
@@ -186,7 +186,7 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(sigsetjmp)
 #endif
 
   mov w0, #0
-  hint #29 // autiasp
+  autiasp
   .cfi_negate_ra_state
   ret
 END(sigsetjmp)
@@ -296,7 +296,7 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(siglongjmp)
   // Set return value.
   cmp w1, wzr
   csinc w0, w1, wzr, ne
-  hint #29 // autiasp
+  autiasp
   .cfi_negate_ra_state
   ret
 END(siglongjmp)

libc/arch-arm64/bionic/vfork.S

@@ -67,7 +67,7 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
 
     // Clean up stack shadow in the parent process.
     // https://github.com/google/sanitizers/issues/925
-    hint #25 // paciasp
+    paciasp
     .cfi_negate_ra_state
     stp x0, x30, [sp, #-16]!
     .cfi_adjust_cfa_offset 16
@@ -81,7 +81,7 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
     .cfi_adjust_cfa_offset -16
     .cfi_restore x0
     .cfi_restore x30
-    hint #29 // autiasp
+    autiasp
     .cfi_negate_ra_state
 
 #endif

libc/arch-common/bionic/crtbegin.c

@@ -49,7 +49,7 @@ __used static void _start_main(void* raw_args) {
 #define POST "; .size _start, .-_start"
 
 #if defined(__aarch64__)
-__asm__(PRE "/* BTI J */ hint #36; mov x0,sp; b _start_main" POST);
+__asm__(PRE "bti j; mov x0,sp; b _start_main" POST);
 #elif defined(__arm__)
 __asm__(PRE "mov r0,sp; b _start_main" POST);
 #elif defined(__i386__)