lang/perl5*: remove workarounds for lld 15 and dtrace enabled
After https://cgit.freebsd.org/src/commit/?id=be39466a1035, there is no
need anymore to patch the perl5 Makefiles to add
"-Wl,--allow-multiple-definition" to the linker flags. They should now
link with lld 15 and later without any issues.