main/vim: add workaround for bug in vim's LDFLAGS modification
abuild-3.8.0_rc1, vim no longer builds with the default
LDFLAGS value provided in
/etc/abuild.conf. This is due to
LDFLAGS modifications performed by vim's build system.
With this commit
--as-needed is no longer the last linker option. Not sure if this is relevant or not.