msun: expose the C23 functions we already support in <math.h>

This is the *pi family of trigonometric functions. Quite a few C23
functions are still missing.  These seem to be:
acospi, acospif, acospil, asinpi, asinpif, asinpil, atan2pi, atan2pif,
atan2pil, atanpi, atanpif, atanpil, canonicalize, canonicalizef,
canonicalizel, compoundn, compoundnf, compoundnl, daddl, ddivl, dfmal,
dmull, dsqrtl, dsubl, exp10, exp10f, exp10l, exp10m1, exp10m1f,
exp10m1l, exp2m1, exp2m1f, exp2m1l, fadd, faddl, fdiv, fdivl, ffma,
ffmal, fmaximum, fmaximum_mag, fmaximum_mag_num, fmaximum_mag_numf,
fmaximum_mag_numl, fmaximum_magf, fmaximum_magl, fmaximum_num,
fmaximum_numf, fmaximum_numl, fmaximumf, fmaximuml, fminimum,
fminimum_mag, fminimum_mag_num, fminimum_mag_numf, fminimum_mag_numl,
fminimum_magf, fminimum_magl, fminimum_num, fminimum_numf,
fminimum_numl, fminimumf, fminimuml, fmul, fmull, fromfp, fromfpf,
fromfpl, fromfpx, fromfpxf, fromfpxl, fsqrt, fsqrtl, fsub, fsubl,
iscanonical, iseqsig, issignaling, issubnormal, iszero, nextdown,
nextdownf, nextdownl, nextup, nextupf, nextupl, pown, pownf, pownl,
powr, powrf, powrl, rootf, rootl, rootn, roundeven, roundevenf,
roundevenl, rsqrt, rsqrtf, rsqrtl, ufromfp, ufromfpf, ufromfpl,
ufromfpx, ufromfpxf, ufromfpxl.

Reviewed by:	imp
Approved by:	markj (mentor)
MFC after:	1 month
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D53783

lib/msun/src/math.h

@@ -508,6 +508,9 @@ long double	lgammal_r(long double, int *);
 void		sincos(double, double *, double *);
 void		sincosf(float, float *, float *);
 void		sincosl(long double, long double *, long double *);
+#endif /* __BSD_VISIBLE */
+
+#if __ISO_C_VISIBLE >= 2023
 double		cospi(double);
 float		cospif(float);
 long double 	cospil(long double);
@@ -517,7 +520,7 @@ long double 	sinpil(long double);
 double		tanpi(double);
 float		tanpif(float);
 long double	tanpil(long double);
-#endif
+#endif /* __ISO_C_VISIBLE >= 2023 */
 
 __END_DECLS