move O_PATH definition back to arch bits

while it's the same for all presently supported archs, it differs at
least on sparc, and conceptually it's no less arch-specific than the
other O_* macros. O_SEARCH and O_EXEC are still defined in terms of
O_PATH in the main fcntl.h.

add O_TMPFILE flag, new in linux 3.11

definition in linux:
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
where __O_TMPFILE and O_DIRECTORY are arch specific

add missing F_GETOWNER_UIDS flag to bits/fcntl.h

PPC port cleaned up, static linking works well now.