Try to unbreak the build on systems where uint64_t isn't something that StringRef::getAsInteger can handle as its second argument

llvm-svn: 138680
diff --git a/clang/lib/ARCMigrate/FileRemapper.cpp b/clang/lib/ARCMigrate/FileRemapper.cpp
index 33a1db4..2705f66 100644
--- a/clang/lib/ARCMigrate/FileRemapper.cpp
+++ b/clang/lib/ARCMigrate/FileRemapper.cpp
@@ -70,7 +70,7 @@
 
   for (unsigned idx = 0; idx+3 <= lines.size(); idx += 3) {
     std::string fromFilename = lines[idx];
-    uint64_t timeModified;
+    unsigned long long timeModified;
     lines[idx+1].getAsInteger(10, timeModified);
     std::string toFilename = lines[idx+2];