fcntl-linux.h: add new definitions and manual updates for open file description locks

Open file description locks have been merged into the Linux kernel for
v3.15.  Add the appropriate command-value definitions and an update to
the manual that describes their usage.
PowerPC: Fix gprof entry point for LE

This patch fixes the ELFv2 gprof entry point since the ABI
does not define function descriptors.  It fixes BZ#17213.