runtime: move runtime.write back to C

It may have to switch stacks, since we are calling
a DLL instead of a system call.

badcallback says where it is, because it is being called
on a Windows stack already.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/5782060

src/pkg/runtime/sys_windows_386.s

@@ -38,28 +38,8 @@ TEXT runtime·asmstdcall(SB),7,$0
 
 	RET
 
-TEXT	runtime·write(SB),7,$24
-	// write only writes to stderr; ignore fd
-	MOVL	$-12, 0(SP)
-	MOVL	SP, BP
-	CALL	*runtime·GetStdHandle(SB)
-	MOVL	BP, SP
-	
-	MOVL	AX, 0(SP)	// handle
-	MOVL	buf+4(FP), DX // pointer
-	MOVL	DX, 4(SP)
-	MOVL	count+8(FP), DX // count
-	MOVL	DX, 8(SP)
-	LEAL	20(SP), DX  // written count
-	MOVL	$0, 0(DX)
-	MOVL	DX, 12(SP)
-	MOVL	$0, 16(SP) // overlapped
-	CALL	*runtime·WriteFile(SB)
-	MOVL	BP, SI
-	RET
-
 TEXT	runtime·badcallback(SB),7,$24
-	// write only writes to stderr; ignore fd
+	// stderr
 	MOVL	$-12, 0(SP)
 	MOVL	SP, BP
 	CALL	*runtime·GetStdHandle(SB)

src/pkg/runtime/sys_windows_amd64.s

@@ -60,29 +60,8 @@ loadregs:
 
 	RET
 
-TEXT runtime·write(SB),7,$48
-	// write only ever writes to stderr; ignore fd
-	MOVQ	$-12, CX // stderr
-	MOVQ	CX, 0(SP)
-	MOVQ	runtime·GetStdHandle(SB), AX
-	CALL	AX
-
-	MOVQ	AX, CX	// handle
-	MOVQ	CX, 0(SP)
-	MOVQ	buf+8(FP), DX // pointer
-	MOVQ	DX, 8(SP)
-	MOVL	count+16(FP), R8 // count
-	MOVQ	R8, 16(SP)
-	LEAQ	40(SP), R9  // written count
-	MOVQ	$0, 0(R9)
-	MOVQ	R9, 24(SP)
-	MOVQ	$0, 32(SP)	// overlapped
-	MOVQ	runtime·WriteFile(SB), AX
-	CALL	AX
-	
-	RET
-
 TEXT runtime·badcallback(SB),7,$48
+	// stderr
 	MOVQ	$-12, CX // stderr
 	MOVQ	CX, 0(SP)
 	MOVQ	runtime·GetStdHandle(SB), AX

src/pkg/runtime/thread_windows.c

@@ -114,6 +114,27 @@ runtime·exit(int32 code)
 	runtime·stdcall(runtime·ExitProcess, 1, (uintptr)code);
 }
 
+int32
+runtime·write(int32 fd, void *buf, int32 n)
+{
+	void *handle;
+	uint32 written;
+
+	written = 0;
+	switch(fd) {
+	case 1:
+		handle = runtime·stdcall(runtime·GetStdHandle, 1, (uintptr)-11);
+		break;
+	case 2:
+		handle = runtime·stdcall(runtime·GetStdHandle, 1, (uintptr)-12);
+		break;
+	default:
+		return -1;
+	}
+	runtime·stdcall(runtime·WriteFile, 5, handle, buf, (uintptr)n, &written, (uintptr)0);
+	return written;
+}
+
 void
 runtime·osyield(void)
 {