indent(1): have the memset invocation somewhat more canonical.

While correct, the previous invocation was somewhat more error prone.

Pointed out by:	delphij, bde

usr.bin/indent/io.c

@@ -630,7 +630,7 @@ parsefont(struct fstate *f, const char *s0)
     const char *s = s0;
     int         sizedelta = 0;
 
-    memset(f, 0, sizeof(struct fstate));
+    memset(f, '\0', sizeof(*f));
     while (*s) {
 	if (isdigit(*s))
 	    f->size = f->size * 10 + *s - '0';