[build2] [build2 0.7-a.0] How to use start-group / end-group in config.c.loptions

[Mueller Tobias (DC-MH/EMF1)]

> If you are building them with build2, then to do this cleanly would require support in build2 (similar to how we do --whole-archive). As a hack, though, this should probably work:
> cc.loptions += -Wl,--start-group
> cc.libs += -Wl,--end-group

With the following setting it works:
config.c.loptions += -Wl,--start-group
config.c.libs += -Wl,--end-group -lspfpmath -lgcc

Thanks a lot!
Tobias