[Bug target/98112] Add -fdirect-access-external-data & drop HAVE_LD_PIE_COPYRELOC

[i at maskray dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98112

--- Comment #3 from Fangrui Song <i at maskray dot me> ---
Are you happy with the option name -f[no-]direct-access-external-data ?
https://reviews.llvm.org/D92633 is what I want to add to Clang.

I want GCC and Clang to use the same option names...