mold used to emit a spurious "recompile with -fPIC" error when creating
a position-dependent executable. This is because we alwyas create
dynamic relocations for importe symbols. If the relocated place is
read-only, we can't apply a dynamic relocation, and we printed out the
error message.
This patch fixes the issue by creating copy relocations and PLTs for
such symbols.
Fixes https://github.com/rui314/mold/issues/116