ext: Bump DRAMPower to avoid compilation issues

This patch bumps DRAMPower to commit
19433a6897ede4bbb19b06694faa8589b5a6569a which contains a small fix
for clang, and a work-around for LTO with gcc 4.6.

ext/drampower/src/MemCommand.h

@@ -159,6 +159,7 @@ class MemCommand {
       }
     }
     assert(false); // Unknown name.
+    return NOP;  // For clang compilation
   }
 
  private:

ext/drampower/src/Utils.h

@@ -54,8 +54,7 @@ throw(std::runtime_error)
   T t;
 
   if (!(is >> f >> t)) {
-    throw std::runtime_error("Cannot convert '" + s + "' to " +
-                             typeid(t).name() + " using fromString");
+    throw std::runtime_error("fromString cannot convert " + s);
   }
 
   return t;