build: update Windows make.bat for Go-based dist

These are corresponding Windows changes for the GOROOT_BOOTSTRAP and
dist changes in https://golang.org/cl/2470

Change-Id: I21da2d63a60d8ae278ade9bb71ae0c314a2cf9b5
Reviewed-on: https://go-review.googlesource.com/2674Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

src/cmd/dist/sys_windows.go

@@ -11,7 +11,7 @@ import (
 
 var (
 	modkernel32       = syscall.NewLazyDLL("kernel32.dll")
-	procGetSystemInfo = syscall.NewProc("GetSystemInfo")
+	procGetSystemInfo = modkernel32.NewProc("GetSystemInfo")
 )
 
 // see http://msdn.microsoft.com/en-us/library/windows/desktop/ms724958(v=vs.85).aspx

src/make.bat

@@ -56,13 +56,17 @@ cd src
 if "x%GOROOT_FINAL%"=="x" set GOROOT_FINAL=%GOROOT%
 set DEFGOROOT=-DGOROOT_FINAL="\"%GOROOT_FINAL:\=\\%\""
 
-echo ##### Building C bootstrap tool.
+echo ##### Building Go bootstrap tool.
 echo cmd/dist
 if not exist ..\bin\tool mkdir ..\bin\tool
-:: Windows has no glob expansion, so spell out cmd/dist/*.c.
-gcc -O2 -Wall -Werror -o cmd/dist/dist.exe -Icmd/dist %DEFGOROOT% cmd/dist/buf.c cmd/dist/build.c cmd/dist/buildgc.c cmd/dist/buildgo.c cmd/dist/buildruntime.c cmd/dist/main.c cmd/dist/windows.c cmd/dist/arm.c
+if "x%GOROOT_BOOTSTRAP%"=="x" set GOROOT_BOOTSTRAP=%HOMEDRIVE%%HOMEPATH%\Go1.4
+if not exist "%GOROOT_BOOTSTRAP%\bin\go.exe" goto bootstrapfail
+setlocal
+set GOROOT=%GOROOT_BOOTSTRAP%
+"%GOROOT_BOOTSTRAP%\bin\go" build -o cmd\dist\dist.exe .\cmd\dist
+endlocal
 if errorlevel 1 goto fail
-.\cmd\dist\dist env -wp >env.bat
+.\cmd\dist\dist env -w -p >env.bat
 if errorlevel 1 goto fail
 call env.bat
 del env.bat
@@ -113,6 +117,10 @@ mkdir "%GOTOOLDIR%" 2>NUL
 copy cmd\dist\dist.exe "%GOTOOLDIR%\"
 goto end
 
+:bootstrapfail
+echo ERROR: Cannot find %GOROOT_BOOTSTRAP%\bin\go.exe
+echo "Set GOROOT_BOOTSTRAP to a working Go tree >= Go 1.4."
+
 :fail
 set GOBUILDFAIL=1
 if x%GOBUILDEXIT%==x1 exit %GOBUILDFAIL%