Merged all interesting difference between the old math.h and the current

one into the latter and removed the former.

This works around the bug that some broken Makefiles add -I.../src/include
to CFLAGS, resulting in the old math.h being preferred and differences
between the headers possibly being fatal.

The merge mainly involves declaring some functions as __pure2 although
they are not yet all strictly free of side effects.

PR:		43544

include/math.h

@@ -1,124 +0,0 @@
-/*
- * Copyright (c) 1985, 1990, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *	This product includes software developed by the University of
- *	California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- *	@(#)math.h	8.1 (Berkeley) 6/2/93
- * $FreeBSD$
- */
-
-#ifndef	_MATH_H_
-#define	_MATH_H_
-
-#define	HUGE_VAL	1e500			/* IEEE: positive infinity */
-
-#if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
-#define	HUGE	HUGE_VAL
-
-#define	M_E		2.7182818284590452354	/* e */
-#define	M_LOG2E		1.4426950408889634074	/* log 2e */
-#define	M_LOG10E	0.43429448190325182765	/* log 10e */
-#define	M_LN2		0.69314718055994530942	/* log e2 */
-#define	M_LN10		2.30258509299404568402	/* log e10 */
-#define	M_PI		3.14159265358979323846	/* pi */
-#define	M_PI_2		1.57079632679489661923	/* pi/2 */
-#define	M_PI_4		0.78539816339744830962	/* pi/4 */
-#define	M_1_PI		0.31830988618379067154	/* 1/pi */
-#define	M_2_PI		0.63661977236758134308	/* 2/pi */
-#define	M_2_SQRTPI	1.12837916709551257390	/* 2/sqrt(pi) */
-#define	M_SQRT2		1.41421356237309504880	/* sqrt(2) */
-#define	M_SQRT1_2	0.70710678118654752440	/* 1/sqrt(2) */
-#endif /* !_ANSI_SOURCE && !_POSIX_SOURCE */
-
-#include <sys/cdefs.h>
-
-/*
- * Most of these functions have the side effect of setting errno, except
- * in the (broken) BSD libm, so they not declared as __pure2.
- */
-__BEGIN_DECLS
-double	acos(double);
-double	asin(double);
-double	atan(double);
-double	atan2(double, double);
-double	ceil(double);
-double	cos(double);
-double	cosh(double);
-double	exp(double);
-double	fabs(double);
-double	floor(double);
-double	fmod(double, double);
-double	frexp(double, int *);	/* fundamentally !__pure2 */
-double	ldexp(double, int);
-double	log(double);
-double	log10(double);
-double	modf(double, double *);	/* fundamentally !__pure2 */
-double	pow(double, double);
-double	sin(double);
-double	sinh(double);
-double	sqrt(double);
-double	tan(double);
-double	tanh(double);
-
-/*
- * These functions are non-ANSI so they can be "right".  The ones that
- * don't set errno in [lib]msun are declared as __pure2.
- */
-#if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
-double	acosh(double);
-double	asinh(double);
-double	atanh(double);
-double	cabs();		/* we can't describe cabs()'s argument properly */
-double	cbrt(double) __pure2;
-double	copysign(double, double) __pure2;
-double	drem(double, double);
-double	erf(double);
-double	erfc(double) __pure2;
-double	expm1(double) __pure2;
-int	finite(double) __pure2;
-double	hypot(double, double);
-int	isinf(double) __pure2;
-int	isnan(double) __pure2;
-double	j0(double);
-double	j1(double);
-double	jn(int, double);
-double	lgamma(double);
-double	log1p(double) __pure2;
-double	logb(double) __pure2;
-double	rint(double) __pure2;
-double	scalb(double, int);
-double	y0(double);
-double	y1(double);
-double	yn(int, double);
-#endif
-
-__END_DECLS
-
-#endif /* !_MATH_H_ */