Add missing file for _ctypes.pyd port to win64 on AMD64.

Modules/_ctypes/libffi_msvc/win64.asm

+PUBLIC	ffi_call_AMD64
+
+EXTRN	__chkstk:NEAR
+EXTRN	ffi_closure_SYSV:NEAR
+
+_TEXT	SEGMENT
+
+;;; ffi_closure_OUTER will be called with these registers set:
+;;;    rax points to 'closure'
+;;;    r11 contains a bit mask that specifies which of the
+;;;    first four parameters are float or double
+;;;
+;;; It must move the parameters passed in registers to their stack location,
+;;; call ffi_closure_SYSV for the actual work, then return the result.
+;;; 
+ffi_closure_OUTER PROC FRAME
+	;; save actual arguments to their stack space.
+	test	r11, 1
+	jne	first_is_float	
+	mov	QWORD PTR [rsp+8], rcx
+	jmp	second
+first_is_float:
+	movlpd	QWORD PTR [rsp+8], xmm0
+
+second:
+	test	r11, 2
+	jne	second_is_float	
+	mov	QWORD PTR [rsp+16], rdx
+	jmp	third
+second_is_float:
+	movlpd	QWORD PTR [rsp+16], xmm1
+
+third:
+	test	r11, 4
+	jne	third_is_float	
+	mov	QWORD PTR [rsp+24], r8
+	jmp	forth
+third_is_float:
+	movlpd	QWORD PTR [rsp+24], xmm2
+
+forth:
+	test	r11, 8
+	jne	forth_is_float	
+	mov	QWORD PTR [rsp+32], r9
+	jmp	done
+forth_is_float:
+	movlpd	QWORD PTR [rsp+32], xmm3
+
+done:
+.ALLOCSTACK 40
+	sub	rsp, 40
+.ENDPROLOG
+	mov	rcx, rax	; context is first parameter
+	mov	rdx, rsp	; stack is second parameter
+	add	rdx, 40		; correct our own area
+	mov	rax, ffi_closure_SYSV
+	call	rax		; call the real closure function
+	;; Here, code is missing that handles float return values
+	add	rsp, 40
+	movd	xmm0, rax	; In case the closure returned a float.
+	ret	0
+ffi_closure_OUTER ENDP
+
+
+;;; ffi_call_AMD64
+
+stack$ = 0
+prepfunc$ = 32
+ecif$ = 40
+bytes$ = 48
+flags$ = 56
+rvalue$ = 64
+fn$ = 72
+
+ffi_call_AMD64 PROC FRAME
+
+	mov	QWORD PTR [rsp+32], r9
+	mov	QWORD PTR [rsp+24], r8
+	mov	QWORD PTR [rsp+16], rdx
+	mov	QWORD PTR [rsp+8], rcx
+.PUSHREG rbp
+	push	rbp
+.ALLOCSTACK 48
+	sub	rsp, 48					; 00000030H
+.SETFRAME rbp, 32
+	lea	rbp, QWORD PTR [rsp+32]
+.ENDPROLOG
+
+	mov	eax, DWORD PTR bytes$[rbp]
+	add	rax, 15
+	and	rax, -16
+	call	__chkstk
+	sub	rsp, rax
+	lea	rax, QWORD PTR [rsp+32]
+	mov	QWORD PTR stack$[rbp], rax
+
+	mov	rdx, QWORD PTR ecif$[rbp]
+	mov	rcx, QWORD PTR stack$[rbp]
+	call	QWORD PTR prepfunc$[rbp]
+
+	mov	rsp, QWORD PTR stack$[rbp]
+
+	movlpd	xmm3, QWORD PTR [rsp+24]
+	movd	r9, xmm3
+
+	movlpd	xmm2, QWORD PTR [rsp+16]
+	movd	r8, xmm2
+
+	movlpd	xmm1, QWORD PTR [rsp+8]
+	movd	rdx, xmm1
+
+	movlpd	xmm0, QWORD PTR [rsp]
+	movd	rcx, xmm0
+
+	call	QWORD PTR fn$[rbp]
+ret_int$:
+ 	cmp	DWORD PTR flags$[rbp], 1 ; FFI_TYPE_INT
+ 	jne	ret_float$
+
+	mov	rcx, QWORD PTR rvalue$[rbp]
+	mov	DWORD PTR [rcx], eax
+	jmp	SHORT ret_nothing$
+
+ret_float$:
+ 	cmp	DWORD PTR flags$[rbp], 2 ; FFI_TYPE_FLOAT
+ 	jne	SHORT ret_double$
+
+ 	mov	rax, QWORD PTR rvalue$[rbp]
+ 	movlpd	QWORD PTR [rax], xmm0
+ 	jmp	SHORT ret_nothing$
+
+ret_double$:
+ 	cmp	DWORD PTR flags$[rbp], 3 ; FFI_TYPE_DOUBLE
+ 	jne	SHORT ret_int64$
+
+ 	mov	rax, QWORD PTR rvalue$[rbp]
+ 	movlpd	QWORD PTR [rax], xmm0
+ 	jmp	SHORT ret_nothing$
+
+ret_int64$:
+  	cmp	DWORD PTR flags$[rbp], 12 ; FFI_TYPE_SINT64
+  	jne	ret_nothing$
+
+ 	mov	rcx, QWORD PTR rvalue$[rbp]
+ 	mov	QWORD PTR [rcx], rax
+ 	jmp	SHORT ret_nothing$
+	
+ret_nothing$:
+	xor	eax, eax
+
+	lea	rsp, QWORD PTR [rbp+16]
+	pop	rbp
+	ret	0
+ffi_call_AMD64 ENDP
+_TEXT	ENDS
+END