[PATCH] GCC 3.3.x/3.4 compatiblity fix in include/linux/init.h

[PATCH] GCC 3.3.x/3.4 compatiblity fix in include/linux/init.h

GCC 3.4 miscompiles the kernel because it silently optimizes away
data placed in the .init.setup section by the __setup() macro.

__attribute__((unused)) does only avoid the warning, but doesn't
mark the data as being used.

Since GCC 3.3, __attribute__((used)) should be applied to such
variables.  The __attribute_used__ macro from linux/compiler.h already
takes care of compiler differences for us.

In this patch, I've gone a step further and proactively fixed that in
all places.