[llvm-cov] Try to fix a test on Windows

Failing bot:
http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/4791

This looks like another stderr redirection issue.

llvm-svn: 312975
diff --git a/llvm/test/tools/llvm-cov/ifdef.c b/llvm/test/tools/llvm-cov/ifdef.c
index 9fd73db..87cb6eb 100644
--- a/llvm/test/tools/llvm-cov/ifdef.c
+++ b/llvm/test/tools/llvm-cov/ifdef.c
@@ -1,6 +1,6 @@
-// RUN: llvm-cov show -instr-profile %S/Inputs/ifdef.profdata %S/Inputs/ifdef.covmapping -dump -path-equivalence=/tmp,%S %s > %t.out 2>&1
+// RUN: llvm-cov show -instr-profile %S/Inputs/ifdef.profdata %S/Inputs/ifdef.covmapping -dump -path-equivalence=/tmp,%S %s > %t.out 2> %t.err.out
 // RUN: FileCheck %s -input-file %t.out -check-prefix=LINE
-// RUN: FileCheck %s -input-file %t.out -check-prefix=HIGHLIGHT
+// RUN: FileCheck %s -input-file %t.err.out -check-prefix=HIGHLIGHT
 
 
 int main() {