This patch allows elf2flt/flthdr's compression options to work in a wider

This patch allows elf2flt/flthdr's compression options to work in a wider
variety of environments (e.g. under MinGW/Win32), by linking with zlib
rather than by using external gzip/gunzip executables. The cp binary
isn't used any more either, and libiberty's make_temp_file() is used
instead of mkstemp() as a more portable way of creating a temporary file.

Also the compression logic is made somewhat clearer, IMO.

Signed-off-by: Julian Brown <julian@codesourcery.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>