[RuntimeDyld] DenseMap -> std::unordered_map

DenseMap is most applicable when both keys and values are small.
In this case, the value violates that assumption, causing quite
significant memory overhead. A std::unordered_map is more appropriate
in this case (or at least fixed the memory problems I was seeing).

Differential Revision: http://reviews.llvm.org/D14910

llvm-svn: 254651
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
index 914efd2..dafd3c8 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
@@ -30,6 +30,7 @@
 #include "llvm/Support/SwapByteOrder.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
+#include <unordered_map>
 #include <system_error>
 
 using namespace llvm;
@@ -264,7 +265,7 @@
   // Relocations to sections already loaded. Indexed by SectionID which is the
   // source of the address. The target where the address will be written is
   // SectionID/Offset in the relocation itself.
-  DenseMap<unsigned, RelocationList> Relocations;
+  std::unordered_map<unsigned, RelocationList> Relocations;
 
   // Relocations to external symbols that are not yet resolved.  Symbols are
   // external when they aren't found in the global symbol table of all loaded