Lagom: Build with -fno-no-semantic-interposition
We build with this in non-lagom builds, and serenity's gcc even adds it
to its CC1_SPEC. Let's use it for lagom too.
Reduces the number of dynamic relocations in liblagom-js.so.0.0.0 (per
`objdump -R`) from 15133 to 14534, and increases its size back to 91M
(95156800 bytes), probably due to more inlining being possible.
This might help perf of lagom binaries.
ec9488a58c
