DwarfDebug: MD5 is always little endian, bswap on big endian platforms.

This makes LLVM emit the same signature regardless of host and target endianess.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187304 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 0d2d02e..7ba1fc1 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1059,8 +1059,9 @@
   Hash.final(Result);
 
   // ... take the least significant 8 bytes and store those as the attribute.
-  uint64_t Signature;
-  memcpy(&Signature, &Result[8], 8);
+  // Our MD5 implementation always returns its results in little endian, swap
+  // bytes appropriately.
+  uint64_t Signature = *reinterpret_cast<support::ulittle64_t *>(Result + 8);
 
   // FIXME: This should be added onto the type unit, not the type, but this
   // works as an intermediate stage.