Make msbuild run in parallel.

vcbuild.bat

@@ -76,7 +76,7 @@ goto run
 
 :msbuild-found
 @rem Build the sln with msbuild.
-msbuild node.sln /t:%target% /p:Configuration=%config% /clp:NoSummary;NoItemAndPropertyList;Verbosity=minimal /nologo
+msbuild node.sln /m /t:%target% /p:Configuration=%config% /clp:NoSummary;NoItemAndPropertyList;Verbosity=minimal /nologo
 if errorlevel 1 goto exit
 
 if defined nosign goto msi
@@ -89,7 +89,7 @@ python "%~dp0tools\getnodeversion.py" > "%temp%\node_version.txt"
 if not errorlevel 0 echo Cannot determine current version of node.js & goto exit
 for /F "tokens=*" %%i in (%temp%\node_version.txt) do set NODE_VERSION=%%i
 heat dir deps\npm -var var.NPMSourceDir -dr NodeModulesFolder -cg NPMFiles -gg -template fragment -nologo -out npm.wxs
-msbuild "%~dp0tools\msvs\msi\nodemsi.sln" /t:Clean,Build /p:Configuration=%config% /p:NodeVersion=%NODE_VERSION% /clp:NoSummary;NoItemAndPropertyList;Verbosity=minimal /nologo
+msbuild "%~dp0tools\msvs\msi\nodemsi.sln" /m /t:Clean,Build /p:Configuration=%config% /p:NodeVersion=%NODE_VERSION% /clp:NoSummary;NoItemAndPropertyList;Verbosity=minimal /nologo
 if errorlevel 1 goto exit
 
 if defined nosign goto run