Fix a memory deallocation error that was crashing q2dm.

Also fix a bunch of compile warnings by changing "char *" to "const char *".
diff --git a/emulator/qtools/post_trace.cpp b/emulator/qtools/post_trace.cpp
index 99525fb..becfc2b 100644
--- a/emulator/qtools/post_trace.cpp
+++ b/emulator/qtools/post_trace.cpp
@@ -137,7 +137,7 @@
   double insn_per_sec = 0;
   if (elapsed_secs != 0)
     insn_per_sec = num_dynamic_insn / elapsed_secs;
-  char *suffix = "";
+  const char *suffix = "";
   if (insn_per_sec >= 1000000) {
     insn_per_sec /= 1000000.0;
     suffix = "M";