This forces make to use bash rather than whatever /bin/sh is linked to. 
Without this, since there are some bash extensions used in the build and when
/bin/sh isn't bash, then the build fails without a clear error message.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>