Add missing long double functions to Cygwin

This patch adds the long double functions missing in newlib to Cygwin.
Apart from some self-written additions (exp10l, finite{f,l}, isinf{f,l},
isnan{f,l}, pow10l) the files are taken from the Mingw-w64 math lib.
Minor changes were required, e.g. substitue _WIN64 with __x86_64__ and
fixing __FLT_RPT_DOMAIN/__FLT_RPT_ERANGE for Cygwin.

Cygwin:
	* math: New subdir with math functions.
	* Makefile.in (VPATH): Add math subdir.
	(MATH_OFILES): List of object files collected from building files in
	math subdir.
	(DLL_OFILES): Add $(MATH_OFILES).
	${CURDIR}/libm.a: Add $(MATH_OFILES) to build.
	* common.din: Add new functions from math subdir.
	* i686.din: Align to new math subdir.  Remove functions now commonly
	available.
	* x86_64.din: Ditto.
	* math.h: math.h wrapper to define mingw structs used in some files in
	math subdir.
	* include/cygwin/version.h: Bump API minor version.

newlib:
	* libc/include/complex.h: Add prototypes for complex long double
	functions.  Only define for Cygwin.
	* libc/include/math.h: Additionally enable prototypes of long double
	functions for Cygwin.  Add Cygwin-only prototypes for dreml, sincosl,
	exp10l and pow10l.  Explain why we don't add them to newlib.
	* libc/include/tgmath.h: Enable long double handling on Cygwin.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/math/ceill.S

@@ -0,0 +1,64 @@
+/**
+ * This file has no copyright assigned and is placed in the Public Domain.
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER.PD within this package.
+ */
+#include <_mingw_mac.h>
+
+	.file	"ceill.S"
+	.text
+#ifdef __x86_64__
+	.align 8
+#else
+	.align 4
+#endif
+	.globl __MINGW_USYMBOL(ceill)
+	.def	__MINGW_USYMBOL(ceill);	.scl	2;	.type	32;	.endef
+__MINGW_USYMBOL(ceill):
+#if defined(_AMD64_) || defined(__x86_64__)
+	fldt	(%rdx)
+	subq	$24,%rsp
+
+	fstcw	8(%rsp)			/* store fpu control word */
+
+	/* We use here %edx although only the low 1 bits are defined.
+	   But none of the operations should care and they are faster
+	   than the 16 bit operations.  */
+	movl	$0x0800,%edx		/* round towards +oo */
+	orl	8(%rsp),%edx
+	andl	$0xfbff,%edx
+	movl	%edx,(%rsp)
+	fldcw	(%rsp)			/* load modified control word */
+
+	frndint				/* round */
+
+	fldcw	8(%rsp)			/* restore original control word */
+
+	addq	$24,%rsp
+	movq	%rcx,%rax
+	movq	$0,8(%rcx)
+	fstpt	(%rcx)
+	ret
+#elif defined(_ARM_) || defined(__arm__)
+	vmrs	r1, fpscr
+	bic		r0, r1, #0x00c00000
+	orr		r0, r0, #0x00400000 /* Round towards Plus Infinity */
+	vmsr	fpscr, r0
+	vcvtr.s32.f64	s0, d0
+	vcvt.f64.s32	d0, s0
+	vmsr	fpscr, r1
+	bx	lr
+#elif defined(_X86_) || defined(__i386__)
+	fldt	4(%esp)
+	subl	$8,%esp
+	fstcw	4(%esp)
+	movl	$0x0800,%edx
+	orl	4(%esp),%edx
+	andl	$0xfbff,%edx
+	movl	%edx,(%esp)
+	fldcw	(%esp)
+	frndint
+	fldcw	4(%esp)
+	addl $8,%esp
+	ret
+#endif