Update ./mlton/.gitignore

Ignore executables created by `make debugged`, `make profile-alloc`,
`make profile-count`, `make profile-time`, and `make traced`.

mlton/.gitignore

@@ -6,6 +6,16 @@
 
 /mlton-compile
 /mlton-compile.exe
+/mlton-compile.debug
+/mlton-compile.debug.exe
+/mlton-compile.alloc
+/mlton-compile.alloc.exe
+/mlton-compile.count
+/mlton-compile.count.exe
+/mlton-compile.time
+/mlton-compile.time.exe
+/mlton-compile.trace
+/mlton-compile.trace.exe
 /mlton-polyml
 /mlton-polyml.exe
 /mlton-polyml.use