Do not raise "inexact" from powerpc64 ceil, floor, trunc (bug 15479).

Continuing fixes for ceil, floor and trunc functions not to raise the
"inexact" exception, this patch fixes the versions used on older
powerpc64 processors.  As was done with the round implementations some
time ago, the save of floating-point state is moved after the first
floating-point operation on the input to ensure that any "invalid"
exception from signaling NaN input is included in the saved state, and
then the whole state gets restored rather than just the rounding mode.

This has no effect on configurations using the power5+ code, since
such processors can do these operations with a single instruction (and
those instructions do not set "inexact", so are correct for TS 18661-1
semantics).

Tested for powerpc64.

	[BZ #15479]
	* sysdeps/powerpc/powerpc64/fpu/s_ceil.S (__ceil): Move save of
	floating-point state after first floating-point operation on
	input.  Restore full floating-point state instead of just rounding
	mode.
	* sysdeps/powerpc/powerpc64/fpu/s_ceilf.S (__ceilf): Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_floor.S (__floor): Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_floorf.S (__floorf): Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_trunc.S (__trunc): Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_truncf.S (__truncf): Likewise.