Prefix build targets with /t: on Windows

Currently, on non-Windows platforms, it is possible to have
a multi-target native module and specify building just some
of the targets using `node-gyp build my_target`.

On Windows, however, specifying the targets to build requires the `/t:`
or `/target:` flag. Without this change you will get an `MSB1008` error
because MSBuild thinks you are trying to specify multiple solutions.

PR-URL: #1164
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/build.js

@@ -23,6 +23,10 @@ function build (gyp, argv, callback) {
     platformMake = 'gmake'
   } else if (process.platform.indexOf('bsd') !== -1) {
     platformMake = 'gmake'
+  } else if (win && argv.length > 0) {
+    argv = argv.map(function(target) {
+      return '/t:' + target
+    })
   }
 
   var release = processRelease(argv, gyp, process.version, process.release)