K 10
svn:author
V 8
jhibbits
K 8
svn:date
V 27
2019-04-27T00:53:41.518458Z
K 7
svn:log
V 451
powerpc: micro-optimize cpu_switch()

Since the non-volatile registers are restored at the end of cpu_switchin (of
the new thread) they're free for us to use for our own purposes.  Load the
PCB_FLAGS into a non-volatile register so it's preserved across the C
function calls that manage FPU and altivec state.  This removes 4 loads from
each file.  Might be a trivial performance improvement (~12 clock cycles per
context switch).

MFC after:	3 weeks

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