[clang] Cleanup fixit.c

This diff removes temporary file t2 in fixit.c and updates the test command accordingly.
NFC.

Test plan:
make check-all

Differential revision: https://reviews.llvm.org/D34066

llvm-svn: 305124

clang/test/FixIt/fixit.c

@@ -1,9 +1,8 @@
 // RUN: %clang_cc1 -pedantic -Wunused-label -verify -x c %s
 // RUN: cp %s %t
 // RUN: not %clang_cc1 -pedantic -Wunused-label -fixit -x c %t
-// RUN: grep -v CHECK %t > %t2
 // RUN: %clang_cc1 -pedantic -Wunused-label -Werror -x c %t
-// RUN: FileCheck -input-file=%t2 %t
+// RUN: grep -v CHECK %t | FileCheck %t
 
 /* This is a test of the various code modification hints that are
    provided as part of warning or extension diagnostics. All of the