Use trunc functions not __trunc functions in glibc libm.

Use trunc functions not __trunc functions in glibc libm.

Continuing the move to use, within libm, public names for libm
functions that can be inlined as built-in functions on many
architectures, this patch moves calls to __trunc functions to call the
corresponding trunc names instead, with asm redirection to __trunc
when the calls are not inlined.

Tested for x86_64, and with build-many-glibcs.py.

	* include/math.h [!_ISOMAC && !(__FINITE_MATH_ONLY__ &&
	__FINITE_MATH_ONLY__ > 0) && !NO_MATH_REDIRECT] (trunc): Redirect
	using MATH_REDIRECT.
	* sysdeps/aarch64/fpu/s_trunc.c: Define NO_MATH_REDIRECT before
	header inclusion.
	* sysdeps/aarch64/fpu/s_truncf.c: Likewise.
	* sysdeps/ieee754/dbl-64/wordsize-64/s_trunc.c: Likewise.
	* sysdeps/ieee754/float128/s_truncf128.c: Likewise.
	* sysdeps/ieee754/dbl-64/s_trunc.c: Likewise.
	* sysdeps/ieee754/flt-32/s_truncf.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_truncl.c: Likewise.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_trunc.c: Likewise.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_truncf.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_trunc.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_truncf.c: Likewise.
	* sysdeps/riscv/rv64/rvd/s_trunc.c: Likewise.
	* sysdeps/riscv/rvf/s_truncf.c: Likewise.
	* sysdeps/sparc/sparc64/fpu/multiarch/s_trunc.c: Likewise.
	* sysdeps/sparc/sparc64/fpu/multiarch/s_truncf.c: Likewise.
	* sysdeps/x86_64/fpu/multiarch/s_trunc.c: Likewise.
	* sysdeps/x86_64/fpu/multiarch/s_truncf.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/s_trunc_template.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Likewise.
	(ceil): Redirect to __ceil.
	(floor): Redirect to __floor.
	(trunc): Redirect to __trunc.
	(__truncl): Call trunc instead of __trunc.
	* sysdeps/powerpc/fpu/math_private.h [_ARCH_PWR5X] (__trunc):
	Remove macro.
	[_ARCH_PWR5X] (__truncf): Likewise.
	* sysdeps/ieee754/dbl-64/e_gamma_r.c (__ieee754_gamma_r): Use
	trunc functions instead of __trunc variants.
	* sysdeps/ieee754/flt-32/e_gammaf_r.c (__ieee754_gammaf_r):
	Likewise.
	* sysdeps/ieee754/ldbl-128/e_gammal_r.c (__ieee754_gammal_r):
	Likewise.
	* sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c (__ieee754_gammal_r):
	Likewise.
	* sysdeps/ieee754/ldbl-96/e_gammal_r.c (__ieee754_gammal_r):
	Likewise.