[sgen] Fix sgen-grep-binprot.

The refactoring that occurred with addition of parallel mark left
sgen-grep-binprot in an uncompilable state.  Fix.

tools/sgen/sgen-grep-binprot.c

@@ -3,6 +3,9 @@
 #include <assert.h>
 #include <glib.h>
 
+#define SGEN_BINARY_PROTOCOL
+#define MONO_INTERNAL
+
 #include <mono/metadata/sgen-protocol.h>
 
 #define SGEN_PROTOCOL_EOF	255