Add CFI to x86 ceil / floor / trunc (bug 16681).

This patch adds CFI to the sysdeps/i386/fpu/ implementations of ceil,
floor and trunc functions, for consistency with other x86 .S files in
glibc which have CFI for stack adjustments.

Tested x86.

	[BZ #16681]
	* sysdeps/i386/fpu/s_ceil.S (__ceil): Add CFI.
	* sysdeps/i386/fpu/s_ceilf.S (__ceilf): Likewise.
	* sysdeps/i386/fpu/s_ceill.S (__ceill): Likewise.
	* sysdeps/i386/fpu/s_floor.S (__floor): Likewise.
	* sysdeps/i386/fpu/s_floorf.S (__floorf): Likewise.
	* sysdeps/i386/fpu/s_floorl.S (__floorl): Likewise.
	* sysdeps/i386/fpu/s_trunc.S (__trunc): Likewise.
	* sysdeps/i386/fpu/s_truncf.S (__truncf): Likewise.
	* sysdeps/i386/fpu/s_truncl.S (__truncl): Likewise.