Use __floor not floor in sinf.

Use __floor not floor in sinf.

The new sinf implementation introduced localplt failures for all
platforms where the compiler did not inline the calls to floor
(converted to trunc by machine-independent optimizations).  This patch
changes the calls to use __floor as normal in libm.

We can't use the public function names floor / floorf / floorl /
floorf128 in libm code in the absence of appropriate asms to redirect
floor/trunc calls, if not inlined, to use the internal names instead
(while avoiding breaking code building the floor functions themselves)
- while having such asms and then calling the public functions
unconditionally would be desirable for optimization (few architectures
have __floor inlines in math_private.h, and once the built-in function
is used you don't need them), using __floor is the minimum safe fix
for the present test regressions.

Tested with build-many-glibcs.py that this fixes the localplt test
failure for arm-linux-gnueabi.

	* sysdeps/ieee754/flt-32/s_sinf.c (SINF_FUNC): Use __floor instead
	of floor.