Window Build Patch - Check for grep and sed

I'm back to the grind again, after messing with php and pecl extensions for awhile. Currently we aren't checking for grep or sed in the windows configure script (which does bad things when you move them around on your system and they can't be found and then you try to compile php-gtk...let's just say "hang" is a kind description) This just adds a quick check that bails if they can't be found because allowing the generator batch file to run without them does naughty things. Can I get an ok to put this in Steph?