debugedit: support compressed debug sections

[dandedrick]

If -gz=zlib is used at compile time the debug sections will be zlib
compressed and need to be decompressed before interpretting. Without
this compressed data will blindly be used as if it were uncompressed
giving inconsistent results.

Support for handling compressed sections was added to elfutils in
version 0.165 so we only do this if we are on that version or newer.

[dandedrick]

In case it is interesting you can test that this fails with the current version of debugedit with the following:

echo "int main(){return 0;}" | gcc -o test.o -c -g -gz=zlib -x c - && /usr/lib/rpm/debugedit -d $(pwd) -b /usr/src/debug -i -l test.list test.o

[dandedrick]

I've run into some odd issues that I think may be related to this change. I'm closing this for now while I do a bit deeper investigation.

[dandedrick]

This change as it was would not return the .debug* sections to the compressed state. I'd like to see if I can make it leave the section in the same compressed state that it was at the start if I can.

[dandedrick]

libelf has issues with writing modified compressed data out so that will have to be fixed first.