Add header guard to Reusables.h [NFC]

llvm-svn: 358724
diff --git a/clang/unittests/StaticAnalyzer/Reusables.h b/clang/unittests/StaticAnalyzer/Reusables.h
index aede503..06aed88 100644
--- a/clang/unittests/StaticAnalyzer/Reusables.h
+++ b/clang/unittests/StaticAnalyzer/Reusables.h
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_CLANG_UNITTESTS_STATICANALYZER_REUSABLES_H
+#define LLVM_CLANG_UNITTESTS_STATICANALYZER_REUSABLES_H
+
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/CrossTU/CrossTranslationUnit.h"
@@ -56,3 +59,5 @@
 
 } // namespace ento
 } // namespace clang
+
+#endif