Add buildispc.bat script for just building the compiler on windows.

buildispc.bat

@@ -0,0 +1,11 @@
+@echo off
+
+REM If LLVM_INSTALL_DIR isn't set globally in your environment,
+REM it can be set here_
+set LLVM_INSTALL_DIR=c:\users\mmp\llvm-dev
+set LLVM_VERSION=3.1svn
+
+REM Both the LLVM binaries and python need to be in the path
+set path=%LLVM_INSTALL_DIR%\bin;%PATH%;c:\cygwin\bin
+
+msbuild ispc.vcxproj /V:m /p:Platform=Win32 /p:Configuration=Release