BUG/MINOR: applet: Fix applet_getword() to not return one extra byte

applet_getword() function is returning one extra byte when a string is
returned because the "ret" variable is not reset before the loop on the
data. The patch also fixes applet_getline().

It is a 3.3-specific issue. No need to backport.

include/haproxy/applet.h

@@ -645,7 +645,7 @@ static inline int applet_getword(const struct appctx *appctx, char *str, int len
 	}
 
 	p = b_head(buf);
-
+	ret = 0;
 	while (max) {
 		*str++ = *p;
 		ret++;