security/tor: Fix build with mips64, powerpc64 and sparc64

Port changes:

• Add USES=compiler:c11
• Add USE_CSTD=gnu99

Situation with MIPS isn't clear, Nathan <ndowens@yahoo.com> says that it works only after adding USES=autoreconf.
The Tor Project should resolve this discrepancy that autoreconf alters the outcome: https://trac.torproject.org/projects/tor/ticket/27901

PR: 231779
Submitted by: Piotr Kubaj <pkubaj@anongoth.pl> (initial version)