Rename the string in clang test missed.

Author: fzou1

clang/test/Driver/relax.s

@@ -8,7 +8,7 @@
 // RUN: llvm-readobj -r %t | FileCheck --check-prefix=REL %s
 
 // REL: R_X86_64_REX_GOTPCRELX foo
-// REL: R_X86_64_REX2_GOTPCRELX foo
+// REL: R_X86_64_CODE_4_GOTPCRELX foo
 
         movq	foo@GOTPCREL(%rip), %rax
         movq	foo@GOTPCREL(%rip), %r16