Update unit tests not to rely on transitive includes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169096 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/ASTMatchers/ASTMatchersTest.cpp

@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ASTMatchersTest.h"
+#include "clang/AST/PrettyPrinter.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Tooling/Tooling.h"