stdio.h: move printf() stuff from <common.h> to <stdio.h>

<common.h> pulls in a lot of headers.  Including it from every .c
file is a bad idea.  We need to remove contents until it contains
nothing.

Move printf() and friends to <stdio.h>.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>