vsnprintf.c: prefix with precision

* vsnprintf.c (BSD_vfprintf): sign and hex-prefix should not be
  counted in precision.  [ruby-dev:47714] [Bug #8916]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58210 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

strftime.c

@@ -582,7 +582,7 @@ rb_strftime_with_timespec(VALUE ftime, const char *format, size_t format_len,
 				goto unknown;
                         }
 			i = snprintf(s, endp - s, (padding == ' ' ? "%+*ld" : "%+.*ld"),
-				     precision + 1, sign * (off / 3600));
+				     precision + (padding == ' '), sign * (off / 3600));
 			if (i < 0) goto err;
 			if (sign < 0 && off < 3600) {
 				*(padding == ' ' ? s + i - 2 : s) = '-';

vsnprintf.c

@@ -1119,11 +1119,11 @@ number:			if ((dprec = prec) >= 0)
 		 */
 		fieldsz = size;
 long_len:
-		if (sign)
-			fieldsz++;
-		if (flags & HEXPREFIX)
-			fieldsz += 2;
 		realsz = dprec > fieldsz ? dprec : fieldsz;
+		if (sign)
+			realsz++;
+		if (flags & HEXPREFIX)
+			realsz += 2;
 
 		/* right-adjusting blank padding */
 		if ((flags & (LADJUST|ZEROPAD)) == 0)
@@ -1145,10 +1145,6 @@ long_len:
 
 		/* leading zeroes from decimal precision */
 		PAD_L(dprec - fieldsz, zeroes);
-		if (sign)
-			fieldsz--;
-		if (flags & HEXPREFIX)
-			fieldsz -= 2;
 
 		/* the string or number proper */
 #ifdef FLOATING_POINT