fltfmt: %.ng is supposed to print a number with n significant figures, but it prints it with n+1. This fixes that behaviour.

sys/src/libc/fmt/fltfmt.c

@@ -187,6 +187,8 @@ found:
 	 * c3 digits of trailing '0'
 	 * c4 digits after '.'
 	 */
+	if(chr == 'g') /* Significant figures. */
+		prec--;
 	c1 = 0;
 	c2 = prec + 1;
 	c3 = 0;