[RFC] Enabling -flto in libstdc++?

[Diego Novillo]

On my nightly tester I force libstdc++ to be built with -flto enabled using

$ make check RUNTESTFLAGS=--target_board=unix/"\{-flto/-O2,-fwhopr/-O2\}"

Recently, this started showing 17 regressions that we don't see in
other testsuites.  It would be useful if we would run libstdc++ with
-flto as well as the regular options.  This will make testing
libstdc++ longer, but it is useful for LTO as several of these tests
are significant.

Would this be OK?


Thanks.  Diego.