Clean up the MachineBasicBlock.h file, percolating #includes into this file.
Patch contributed by Morten Ofstad

llvm-svn: 17251
diff --git a/llvm/lib/CodeGen/VirtRegMap.cpp b/llvm/lib/CodeGen/VirtRegMap.cpp
index 49cebe8..39707db 100644
--- a/llvm/lib/CodeGen/VirtRegMap.cpp
+++ b/llvm/lib/CodeGen/VirtRegMap.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
+#include <algorithm>
 using namespace llvm;
 
 namespace {