Strip binaries in bundles

[probonopd]

Currently binaries generated by nix2appimage.sh are very large. This, in part, is due to the fact that they are not stripped.

[probonopd]

Also, the *.a files should be removed.

[probonopd]

By these two measures, I could bring down the Inkscape AppImage from 161M to 142M.

[probonopd]

Same goes for *.la.

[matthewbauer]

A couple of notes:

• I'd prefer to have most of this stuff "handled in NixPkgs" - that is get the package itself to be smaller.
  • see Binaries are not stripped NixOS/nixpkgs#21667 on stripping binaries
  • For instance in Inkscape, one of the biggest offenders is openblas.
• That said, there are definitely some things that are harder to get right. The .la files are fairly small and definitely not needed at all at runtime. We can definitely just delete these and maybe some other things (man pages?).