xray: fix assembly macro definition

  projects/compiler-rt/lib/xray/xray_trampoline_x86_64.S:33:7: error: unexpected token in '.endm' directive
  .endm SAVE_REGISTERS
	^
  projects/compiler-rt/lib/xray/xray_trampoline_x86_64.S:52:7: error: unexpected token in '.endm' directive
  .endm RESTORE_REGISTERS
	^

Remove the trailing name on the `.endm` which does not take the name of the
macro.  This should bring the compiler-rt build bot back into working state.

llvm-svn: 289852