Move lib/Runtime to runtime/, and build after everything else.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107327 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile b/Makefile
index fd34ca3..f871c25 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@
 
 IS_TOP_LEVEL := 1
 CLANG_LEVEL := .
-DIRS := include lib tools docs
+DIRS := include lib tools runtime docs
 
 PARALLEL_DIRS :=