Remove redundant declaration.

Automatically reformat extlinux/main.c using Nindent.

Do this for all files except HDT, gPXE and externally maintained
libraries (zlib, tinyjpeg, libpng).

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Centralize more (most) of the version number machinery to version.pl.

When we didn't find the filesystem in /proc/mounts, we would go
through /etc/mtab, but then completely botch the parsing thereof.
Move the parsing to a common function to avoid this problem.

Assemble all files to ELF instead of using the NASM built-in linker.
This can enable us to do actual linking in the future.