configure: Use lld if available
configure: Use lld if available

This depends on the patch

mk: avoid combining -r and -export-dynamic linker options

being added to dpdk.

I benchmarked this on top of my patches to get a reproducible build. I
first compiled with ccache, deleted the build directory and recompiled
so that all the "gcc -c" invocations were served by ccache. The times
of the second "ninja release" invocations were:

lld:
ninja release  155.68s user 71.89s system 2077% cpu 10.953 total

gold:
ninja release  953.79s user 254.71s system 2533% cpu 47.699 total

Signed-off-by: Rafael Ávila de Espíndola <1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>
Message-Id: <20200127171516.26268-1-1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>

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