help.h: fix coding style

We want a space after the `while` keyword.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

help.h

@@ -15,7 +15,7 @@ struct cmdnames {
 static inline void mput_char(char c, unsigned int num)
 {
-	while(num--)
+	while (num--)
 		putchar(c);
 }