mips: switch to generic compat rt_sigprocmask()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc arch/mips/Kconfig
Simple merge

diff --cc arch/mips/kernel/scall64-n32.S
Simple merge

diff --cc arch/mips/kernel/scall64-o32.S
Simple merge

diff --cc arch/mips/kernel/signal32.c
Simple merge