package/gcc: use binutils wrappers for target libs
This will use gcc-ar, gcc-nm and gcc-ranlib instead of the
normal binutils tools. The difference is that with the
wrappers, gcc plugins will be automatically picked up,
which is necessary to build with LTO.
With this enabled, it is possible to build everything (including libgcc
and libstdc++) with LTO by setting BR2_TARGET_OPTIMIZATION="-flto".
Note that you'd expect that the GCC build system would automatically do
this when --enable-lto is set, but this is not the case. There are some
open bugs [1][2] to allow building libgcc and libstdc++ with LTO support
but it's apparently not done yet.
Note that there are also reports of problems building libstdc++ with LTO
[3], but it seems that's no longer a problem (and the bug didn't get
updated).
Signed-off-by: Norbert Lange <nolange79@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59893
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77278
[3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60160
Norbert Lange