curl: point out unnecessary uses of -X in verbose mode

It uses 'Note:' as a prefix as opposed to the common 'Warning:' to take
down the tone a bit.

It adds a warning for using -XHEAD on other methods becasue that may
lead to a hanging connection.

src/tool_msgs.h

@@ -24,6 +24,7 @@
 #include "tool_setup.h"
 
 void warnf(struct GlobalConfig *config, const char *fmt, ...);
+void notef(struct GlobalConfig *config, const char *fmt, ...);
 
 void helpf(FILE *errors, const char *fmt, ...);