chore: use -rdynamic instead of -export-dynamic

It has been observed that on Fedora -export-dynamic triggers some
reincarnation of this bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47390

TLDR: it treated leading -e as entrypoint argument so resulting binary
was completely broken, i e there was no main in it and entrypoint was
set to unrelated deregister_tm_clones. Big thanks to @gmoshkin for
finding the solution and to @funbringer for assistance with debugging