[PATCH] boot loader fixes

This patch has various boot loader fixes.

1.  Add capability to allow BOOT_COMCONSOLE_SPEED=0, which is 
extension of the following commit:

http://docs.freebsd.org/cgi/mid.cgi?200411241539.iAOFd40s041084

2.  Remove '-fno-unit-at-a-time' from boot2.c build.  It seems there 
were two problems.

'-fno-unit-at-a-time' and '-mrtd' conflict:
http://docs.freebsd.org/cgi/mid.cgi?200408062059.i76KxTBW026143

This problem seems to be resolved by importing new GCC.

static memcpy():
http://docs.freebsd.org/cgi/mid.cgi?20040807011451.GA51119

I can be easily resolved by removing static as suggested.

3.  Add more bound checks.  Note that comconsole speed check is 
currently disabled because of size limitation. :-(

4.  Allow '-S0' or simply '-S'.  This is not to change serial speed.

5.  Fix array size bug.

6.  Clean up style for more readability.

Please test.

Thanks,

Jung-uk Kim