x86-64: Replace assembly versions of e_expf with generic e_expf.c

x86-64: Replace assembly versions of e_expf with generic e_expf.c

This patch replaces x86-64 assembly versions of e_expf with generic
e_expf.c.  For workload-spec2017.wrf, on Nehalem, it improves
performance by:

                           Before            After     Improvement
reciprocal-throughput      36.039           20.7749       73%
latency                    58.8096          40.8715       43%

On Skylake, it improves

                           Before            After     Improvement
reciprocal-throughput      18.4436          11.1693       65%
latency                    47.5162          37.5411       26%

	* sysdeps/x86_64/fpu/e_expf.S: Removed.
	* sysdeps/x86_64/fpu/multiarch/e_expf-fma.S: Likewise.
	* sysdeps/x86_64/fpu/w_expf.c: Likewise.
	* sysdeps/x86_64/fpu/libm-test-ulps: Updated for generic
	e_expf.c.
	* sysdeps/x86_64/fpu/multiarch/Makefile (CFLAGS-e_expf-fma.c):
	New.
	* sysdeps/x86_64/fpu/multiarch/e_expf-fma.c: New file.
	* sysdeps/x86_64/fpu/multiarch/e_expf.c (__redirect_ieee754_expf):
	Renamed to ...
	(__redirect_expf): This.
	(SYMBOL_NAME): Changed to expf.
	(__ieee754_expf): Renamed to ...
	(__expf): This.
	(__GI___expf): This.
	(__ieee754_expf): Add strong_alias.
	(__expf_finite): Likewise.
	(__expf): New.
	Include <sysdeps/ieee754/flt-32/e_expf.c>.