[syslinux] Enhanced MDISKCHK.COM and MEMDISK patches

[Shao Miller]

Good day to all,

Gert Hulselmans requested a feature for MDISKCHK.COM that would function 
roughly like GETARGS.COM[1] by Murali Krishnan Ganapathy: DOS SET 
command output for MEMDISK kernel arguments passed by previous 
boot-loaders.  He also needed to support the case for 
MEMDISK-in-a-MEMDISK type situations, where all MEMDISK kernel arguments 
could be gathered together and output as a list of DOS SET commands.

One way to search for "outer" MEMDISKs is via mBFT and/or INT 13h "safe 
hook" scanning.  To support this, some modifications to MEMDISK were 
needed to allow the sharing of common structure information to 
MDISKCHK.COM's source code.  Also, one MEMDISK bug was found.

If you are currently a GETARGS.COM user and your batch file goes like:

@echo off
getargs.com>setenv.bat
call setenv.bat>nul

you can accomplish the same thing with MDISKCHK.COM using:

@echo off
echo @echo off>setenv.bat
mdiskchk.com -b>>setenv.bat
call setenv.bat>nul

Some of the work done on MEMDISK might be useful for COM32 modules at 
some point, too.

How about getting this[2] merged?  Thanks for your time,

- Shao Miller

[1] http://people.cs.uchicago.edu/~gmurali/gui/downloads.html
[2] 
http://git.etherboot.org/?p=people/sha0/syslinux.git;a=log;h=refs/heads/mdiskchk_enhanced