[modules] Setup the import location of a module file and use it
as the include location of the main file of an imported module.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168061 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index a34244d..f06b428 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -1030,7 +1030,7 @@
         continue;
 
       Record.push_back((unsigned)(*M)->Kind); // FIXME: Stable encoding
-      // FIXME: Write import location, once it matters.
+      AddSourceLocation((*M)->ImportLoc, Record);
       // FIXME: This writes the absolute path for AST files we depend on.
       const std::string &FileName = (*M)->FileName;
       Record.push_back(FileName.size());