Possible improvements to build system

[phcoder <phcoder@gmail.com>]

Hello, I noticed that updating some pieces of code needs modification of 
nearly all *.rmk. IMO it's bad thing because e.g. it easily brings 
different architectures out of sync. My improvement propositions:
1. normal.mod
There is one part which is CPU-dependent - setjmp.S. t's used only in
static grub_err_t
rescue_command (struct grub_arg_list *state __attribute__ ((unused)),
                 int argc __attribute__ ((unused)),
                 char **args __attribute__ ((unused)))
{
   grub_longjmp (grub_exit_env, 0);

   /* Never reach here.  */
   return 0;
}

We could replace this longjmp by a call of grub_enter_rescue_mode and 
move the call to attempt_normal_mode to grub_main.
Another possibility is to create a symlink normal/cpu during configure 
time and then during build time just use normal/cpu/setjmp.S
2. ata.mod, hdparm.mod, ata_pthru.mod, usbms.mod, ohci.mod, uhci.mod, 
usbtest.mod, usb.mod, memdisk.mod
I don't see why these modules are in i386-pc.rmk and not in common.rmk
3. kernel.img, grub-setup
These contain a number of files shared by all platforms. Like e.g. 
filesystems. I propose to create an additional file common-pre.rmk which 
could contain the variables like
FS_files=...
which platform-specific files can use later
-- 

Regards
Vladimir 'phcoder' Serbinenko