first commit of the new libm!

thanks to the hard work of Szabolcs Nagy (nsz), identifying the best
(from correctness and license standpoint) implementations from freebsd
and openbsd and cleaning them up! musl should now fully support c99
float and long double math functions, and has near-complete complex
math support. tgmath should also work (fully on gcc-compatible
compilers, and mostly on any c99 compiler).

based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from
nsz's libm git repo, with some additions (dummy versions of a few
missing long double complex functions, etc.) by me.

various cleanups still need to be made, including re-adding (if
they're correct) some asm functions that were dropped.

src/math/__sinl.c

@@ -0,0 +1,61 @@
+/* origin: FreeBSD /usr/src/lib/msun/ld80/k_sinl.c */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ * Copyright (c) 2008 Steven G. Kargl, David Schultz, Bruce D. Evans.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+/*
+ * ld80 version of __sin.c.  See __sin.c for most comments.
+ */
+/*
+ * Domain [-0.7854, 0.7854], range ~[-1.89e-22, 1.915e-22]
+ * |sin(x)/x - s(x)| < 2**-72.1
+ *
+ * See __cosl.c for more details about the polynomial.
+ */
+
+static const double half = 0.5;
+
+// FIXME
+/* Long double constants are slow on these arches, and broken on i386. */
+static const volatile double
+S1hi = -0.16666666666666666,      /* -0x15555555555555.0p-55 */
+S1lo = -9.2563760475949941e-18;   /* -0x15580000000000.0p-109 */
+#define S1      ((long double)S1hi + S1lo)
+
+#if 0
+static const long double
+S1 = -0.166666666666666666671L;   /* -0xaaaaaaaaaaaaaaab.0p-66 */
+#endif
+
+static const double
+S2 =  0.0083333333333333332,      /*  0x11111111111111.0p-59 */
+S3 = -0.00019841269841269427,     /* -0x1a01a01a019f81.0p-65 */
+S4 =  0.0000027557319223597490,   /*  0x171de3a55560f7.0p-71 */
+S5 = -0.000000025052108218074604, /* -0x1ae64564f16cad.0p-78 */
+S6 =  1.6059006598854211e-10,     /*  0x161242b90243b5.0p-85 */
+S7 = -7.6429779983024564e-13,     /* -0x1ae42ebd1b2e00.0p-93 */
+S8 =  2.6174587166648325e-15;     /*  0x179372ea0b3f64.0p-101 */
+
+long double __sinl(long double x, long double y, int iy)
+{
+	long double z,r,v;
+
+	z = x*x;
+	v = z*x;
+	r = S2+z*(S3+z*(S4+z*(S5+z*(S6+z*(S7+z*S8)))));
+	if (iy == 0)
+		return x+v*(S1+z*r);
+	return x-((z*(half*y-v*r)-y)-v*S1);
+}
+#endif