Fix non libtool build
Currently, g-ir-scanner is completely broken with anything that is not a "-la" file. For example, all meson builds are incorrect I think. It has multiple issues:
- It puts the "-L"s after the "-l", meaning they're never used. So it will only works if the library is in the root directory with meson. This means that in most cases, it will scan the system installed library instead of the one your are building.
- It tries to find the library name with "ldd" for non-libtool libraries, that obviously fails for static libraries. I just removed the check because we have no idea way to know if it's a static library or not.
- Accept absolute library filenames for non-.la files, this makes it easier for the build system to ensure that the right one is used and avoid fiddling with -Ls.