Remove unused math files

Remove unused math files

Remove empty files due to the sin/cos improvements: k_sinf.c, k_cosf.c,
k_cos.c, k_sin.c.  After the tanf change s_rem_pio2f.c and k_rem_pio2f.c
(and the ia64, m68k and powerpc equivalents) are no longer used,
so remove them.  All e_rem_pio2.c files were already empty or commented
out, so remove them too.  Passes build-many-glibcs.

	* math/Makefile: Remove empty files k_sin(f).c, k_cos(f).c.
	Remove unused files e_rem_pio2(f).c, k_rem_pio2f.c.
	* sysdeps/i386/fpu/e_rem_pio2.c: Delete file.
	* sysdeps/ia64/fpu/e_rem_pio2.c: Likewise.
	* sysdeps/ia64/fpu/e_rem_pio2f.c: Likewise.
	* sysdeps/ia64/fpu/k_rem_pio2f.c: Likewise.
	* sysdeps/ieee754/dbl-64/e_rem_pio2.c: Likewise.
	* sysdeps/ieee754/dbl-64/k_cos.c: Likewise.
	* sysdeps/ieee754/dbl-64/k_sin.c: Likewise.
	* sysdeps/ieee754/flt-32/e_rem_pio2f.c: Likewise.
	* sysdeps/ieee754/flt-32/k_cosf.c: Likewise.
	* sysdeps/ieee754/flt-32/k_rem_pio2f.c: Likewise.
	* sysdeps/ieee754/flt-32/k_sinf.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/e_rem_pio2.c: Likewise
	* sysdeps/m68k/m680x0/fpu/e_rem_pio2f.c: Likewise
	* sysdeps/m68k/m680x0/fpu/k_rem_pio2f.c: Likewise
	* sysdeps/powerpc/fpu/e_rem_pio2f.c: Likewise.
	* sysdeps/powerpc/fpu/k_rem_pio2f.c: Likewise.