Performance fixes relating to floating point

Removes unneccesary usage of soft-float double usage. The reason for the
useless double math being done were broken standard C++ functions:
atanh<float>, sqrt<float>, asinh<float>, operator/<float>. This was in
turn caused by missing float versions of C++ functions hypot, atan2,
logb, scalbn.

A logbf implementation was missing from the libm, so I added one from
openlibm.

liba/Makefile

@@ -65,6 +65,7 @@ liba_src += $(addprefix liba/src/external/openbsd/, \
   s_frexp.c \
   s_log1pf.c \
   s_logb.c \
+  s_logbf.c \
   s_modf.c \
   s_modff.c \
   s_rint.c \

liba/src/external/openbsd/s_logbf.c

@@ -0,0 +1,42 @@
+/* s_logbf.c -- float version of s_logb.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Taken from openlibm at 5b0e7e981321687ac0abe711fdeb30adcd9da932 and
+ * modified for Numworks Epsilon by Neven Sajko <nsajko@gmail.com>
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+//__FBSDID("$FreeBSD: src/lib/msun/src/s_logbf.c,v 1.9 2008/02/22 02:30:35 das Exp $");
+
+#include "math.h"
+
+#include "math_private.h"
+
+static const float
+two25 = 3.355443200e+07;		/* 0x4c000000 */
+
+float
+logbf(float x)
+{
+	int32_t ix;
+	GET_FLOAT_WORD(ix,x);
+	ix &= 0x7fffffff;			/* high |x| */
+	if(ix==0) return (float)-1.0/fabsf(x);
+	if(ix>=0x7f800000) return x*x;
+	if(ix<0x00800000) {
+		x *= two25;		 /* convert subnormal x to normal */
+		GET_FLOAT_WORD(ix,x);
+		ix &= 0x7fffffff;
+		return (float) ((ix>>23)-127-25);
+	} else
+		return (float) ((ix>>23)-127);
+}