Add 'env' in hopes of making this test pass on Windows.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154785 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeCompletion/preamble.c b/test/CodeCompletion/preamble.c
index 98ad679..f322e09 100644
--- a/test/CodeCompletion/preamble.c
+++ b/test/CodeCompletion/preamble.c
@@ -3,5 +3,5 @@
   struct X x;
   x.
 
-// RUN: CINDEXTEST_EDITING=1 c-index-test -code-completion-at=%s:4:5 -Xclang -code-completion-patterns  %s | FileCheck -check-prefix=CHECK-CC1 %s
+// RUN: env CINDEXTEST_EDITING=1 c-index-test -code-completion-at=%s:4:5 -Xclang -code-completion-patterns  %s | FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: FieldDecl:{ResultType int}{TypedText m} (35) (parent: StructDecl 'X')