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/frexpl.S

@@ -0,0 +1,130 @@
+/**
+ * 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>
+
+/*
+ * frexpl(long double x, int* expnt) extracts the exponent from x.
+ * It returns an integer power of two to expnt and the significand
+ * between 0.5 and 1 to y.  Thus  x = y * 2**expn.
+ */ 
+#ifdef __x86_64__
+	.align 8
+#else
+	.align 2
+#endif
+.globl __MINGW_USYMBOL(frexpl)
+__MINGW_USYMBOL(frexpl):
+#ifdef __x86_64__
+	pushq %rbp
+	movq %rsp,%rbp
+	subq $48,%rsp
+	pushq %rsi
+	fldt (%rdx)
+	movq %rcx,%r9
+	fld %st(0)
+	fstpt -12(%rbp)
+	leaq -4(%rbp),%rcx
+	movw -4(%rbp),%dx
+	andl $32767,%edx
+	jne L25
+	fldz
+	fucompp
+	fnstsw %ax
+	andb $68,%ah
+	xorb $64,%ah
+	jne L21
+	movl $0,(%r8)
+	fldz
+	jmp L24
+	.align 4,0x90
+	.align 4,0x90
+L21:
+	fldt -12(%rbp)
+	fadd %st(0),%st
+	fstpt -12(%rbp)
+	decl %edx
+	movw (%rcx),%si
+	andl $32767,%esi
+	jne L22
+	cmpl $-66,%edx
+	jg L21
+L22:
+	add %esi,%edx
+	jmp L19
+	.align 2,0x90
+L25:
+	fstp %st(0)
+L19:
+	addl $-16382,%edx
+	movl %edx,(%r8)
+	movw (%rcx),%ax
+	andl $-32768,%eax
+	orl $16382,%eax
+	movw %ax,(%rcx)
+	fldt -12(%rbp)
+L24:
+	popq %rsi
+	movq	%r9,%rax
+	movq	$0,8(%r9)
+	fstpt	(%r9)
+	leave
+	ret
+#else
+	pushl %ebp
+	movl %esp,%ebp
+	subl $24,%esp
+	pushl %esi
+	pushl %ebx
+	fldt 8(%ebp)
+	movl 20(%ebp),%ebx
+	fld %st(0)
+	fstpt -12(%ebp)
+	leal -4(%ebp),%ecx
+	movw -4(%ebp),%dx
+	andl $32767,%edx
+	jne L25
+	fldz
+	fucompp
+	fnstsw %ax
+	andb $68,%ah
+	xorb $64,%ah
+	jne L21
+	movl $0,(%ebx)
+	fldz
+	jmp L24
+	.align 2,0x90
+	.align 2,0x90
+L21:
+	fldt -12(%ebp)
+	fadd %st(0),%st
+	fstpt -12(%ebp)
+	decl %edx
+	movw (%ecx),%si
+	andl $32767,%esi
+	jne L22
+	cmpl $-66,%edx
+	jg L21
+L22:
+	addl %esi,%edx
+	jmp L19
+	.align 2,0x90
+L25:
+	fstp %st(0)
+L19:
+	addl $-16382,%edx
+	movl %edx,(%ebx)
+	movw (%ecx),%ax
+	andl $-32768,%eax
+	orl $16382,%eax
+	movw %ax,(%ecx)
+	fldt -12(%ebp)
+L24:
+	leal -32(%ebp),%esp
+	popl %ebx
+	popl %esi
+	leave
+	ret
+#endif