--as-needed is broken with gnu ld

it seems that --as-needed is ignored by gnu ld for libraries between --start-group/--end-group. maybe meson should put shared libraries outside of group. gold works properly btw, so another option is to use gold by default

Start by tracing how Meson emits linker arguments for --start-group/--end-group and --as-needed when using GNU ld, then compare the behavior with gold. Determine whether shared libraries should be placed outside the group or whether gold should be selected by default. Done means --as-needed is honored for libraries in the relevant GNU ld configuration, with coverage for the linker behavior.

Written by the indexing model from the issue text.