init.h: remove obsolete content

Remove apparently obsolete content from init.h referring to gcc 2.9x
and to "no_module_init".

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>