Revert "lib/rwsem.c: fix compatibility issues with Linux 3.1.y"

This reverts commit 40a8b28e2d19e8b4d62278935db5a5be745583eb.
Revert "rwsem: steal writing sem for better performance"

This reverts commit 52e05aa3383b32a852e02515ccbab92ffcdff423.
Revert "rwsem-spinlock: let rwsem write lock stealable"

This reverts commit 89eb74f331b7f4fd2420a4b834ff3c884a65e261.