Turn off dump/emit routines when building minimal subzero.

Remove the dump/emit routines when ALLOW_DUMP=0. Also fixes some
verbosity messages to not print if ALLOW_DUMP=0. Note: emit routines
needed for emitIAS are not turned off.

BUG=None
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/686913005
diff --git a/src/IceTypes.cpp b/src/IceTypes.cpp
index 975001d..455aa0c 100644
--- a/src/IceTypes.cpp
+++ b/src/IceTypes.cpp
@@ -260,6 +260,8 @@
 }
 
 void FuncSigType::dump(Ostream &Stream) const {
+  if (!ALLOW_DUMP)
+    return;
   Stream << ReturnType << " (";
   bool IsFirst = true;
   for (const Type ArgTy : ArgList) {