strip don't mmap debug output file.

strip don't mmap debug output file.

Using ELF_C_WRITE_MMAP sometimes causes unexpected errors when disk
space is low. When writing out the file, the output file is first
extended so that it covers the whole file/mmap size. But it might
be that the file system allowed the extension as a sparse file. In
that case writing to the file through the mmap might still fail and
produce a SIGBUS if the disk is full. This is confusing to the user.

Using ELF_C_WRITE will produce "normal" errors when the file cannot
be written out. It also seems to use less memory because the debug
file is created from scratch. So the memory is first read into the
ELF data structure buffers, then written out as a whole. In this case
the mmap output buffer is just overhead.

Signed-off-by: Mark Wielaard <mark@klomp.org>