Revert "[sanitizer] Support Intel CET"

This reverts commit fdf4c03.

Breaks macOS bots, e.g. https://crbug.com/1257863.
Still figuring out if this is actually supported on macOS. Other places
that include <cet.h> only do so on Linux.

Author: aeubanks

compiler-rt/lib/hwasan/hwasan_setjmp_x86_64.S

@@ -35,7 +35,6 @@
 ASM_TYPE_FUNCTION(__interceptor_setjmp)
 __interceptor_setjmp:
   CFI_STARTPROC
-  _CET_ENDBR
   xorl %esi, %esi
   jmp	__interceptor_sigsetjmp
   CFI_ENDPROC
@@ -45,7 +44,6 @@ ASM_SIZE(__interceptor_setjmp)
 ASM_TYPE_FUNCTION(__interceptor_sigsetjmp)
 __interceptor_sigsetjmp:
   CFI_STARTPROC
-  _CET_ENDBR
 
   // Save callee save registers.
   mov %rbx, (0*8)(%rdi)

compiler-rt/lib/sanitizer_common/sanitizer_asm.h

@@ -66,7 +66,3 @@
 #else
 #define NO_EXEC_STACK_DIRECTIVE
 #endif
-
-#if defined(__x86_64__) || defined(__i386__)
-#include <cet.h>
-#endif

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_vfork_i386.inc.S

@@ -6,7 +6,6 @@
 .globl ASM_WRAPPER_NAME(vfork)
 ASM_TYPE_FUNCTION(ASM_WRAPPER_NAME(vfork))
 ASM_WRAPPER_NAME(vfork):
-        _CET_ENDBR
         // Store return address in the spill area and tear down the stack frame.
         sub     $12, %esp
         call    COMMON_INTERCEPTOR_SPILL_AREA

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_vfork_x86_64.inc.S

@@ -6,7 +6,6 @@
 .globl ASM_WRAPPER_NAME(vfork)
 ASM_TYPE_FUNCTION(ASM_WRAPPER_NAME(vfork))
 ASM_WRAPPER_NAME(vfork):
-        _CET_ENDBR
         // Store return address in the spill area and tear down the stack frame.
         push    %rcx
         call    COMMON_INTERCEPTOR_SPILL_AREA

compiler-rt/lib/tsan/rtl/tsan_rtl_amd64.S

@@ -13,7 +13,6 @@ ASM_HIDDEN(__tsan_trace_switch)
 .globl ASM_SYMBOL(__tsan_trace_switch_thunk)
 ASM_SYMBOL(__tsan_trace_switch_thunk):
   CFI_STARTPROC
-  _CET_ENDBR
   # Save scratch registers.
   push %rax
   CFI_ADJUST_CFA_OFFSET(8)
@@ -94,7 +93,6 @@ ASM_HIDDEN(__tsan_report_race)
 .globl ASM_SYMBOL(__tsan_report_race_thunk)
 ASM_SYMBOL(__tsan_report_race_thunk):
   CFI_STARTPROC
-  _CET_ENDBR
   # Save scratch registers.
   push %rax
   CFI_ADJUST_CFA_OFFSET(8)
@@ -187,7 +185,6 @@ ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(setjmp))
 ASM_SYMBOL_INTERCEPTOR(setjmp):
 #endif
   CFI_STARTPROC
-  _CET_ENDBR
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)
@@ -229,7 +226,6 @@ ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(setjmp))
 ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(_setjmp))
 ASM_SYMBOL_INTERCEPTOR(_setjmp):
   CFI_STARTPROC
-  _CET_ENDBR
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)
@@ -271,7 +267,6 @@ ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
 ASM_SYMBOL_INTERCEPTOR(sigsetjmp):
 #endif
   CFI_STARTPROC
-  _CET_ENDBR
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)
@@ -328,7 +323,6 @@ ASM_SIZE(ASM_SYMBOL_INTERCEPTOR(sigsetjmp))
 ASM_TYPE_FUNCTION(ASM_SYMBOL_INTERCEPTOR(__sigsetjmp))
 ASM_SYMBOL_INTERCEPTOR(__sigsetjmp):
   CFI_STARTPROC
-  _CET_ENDBR
   // save env parameter
   push %rdi
   CFI_ADJUST_CFA_OFFSET(8)