Add a custom initialize hook for clang tools + minor fixes in CustomCompilationDatabase.h

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160369 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Tooling/CompilationDatabase.cpp b/lib/Tooling/CompilationDatabase.cpp
index 802a4c3..3139cc2 100644
--- a/lib/Tooling/CompilationDatabase.cpp
+++ b/lib/Tooling/CompilationDatabase.cpp
@@ -130,7 +130,7 @@
 findCompilationDatabaseFromDirectory(StringRef Directory) {
 #ifdef USE_CUSTOM_COMPILATION_DATABASE
   if (CompilationDatabase *DB =
-      ::findCompilationDatabaseForDirectory(Directory))
+      ::clang::tooling::findCompilationDatabaseForDirectory(Directory))
     return DB;
 #endif
   while (!Directory.empty()) {