header (C) fixes
Extended RTOnce with termination cleanups. (Changes existing structures and functions.)
Runtime/pathhost-posix.cpp: missing include
*: spelling fixes, thanks Timeless!
iprt/symlink.h: Initial code (only tested on linux).
iprt/RTDirRead: fixed memory leak introduced in r60863
Don't use RTStrCopyEx with RTSTR_MAX.
iprt: More path conversion avoidance.
generic/pathhost-generic.cpp -> r3/posix/pathhost-posix.cpp; rewrote pathhost-generic.cpp as a UTF-8 pass through.