Cleanup: Remove devel/llvm[789]0
* remove old devel/llvm70
* remove old devel/llvm80
* remove old devel/llvm90
* remove ports explicitely depending on either of the three
Differential Revision: https://reviews.freebsd.org/D37936
Update to 9.0.0 release.
Attempt to fix linkin of openmp when the linker isn't LLD.
Enable LLD_LINK by default. It is increasingly the case that lld is a
safe choice so just go with it.
Enable SecurePLT on PowerPC for FreeBSD 13 and up.
PR: 240730, 240737