configure: supply target_arch define to gyp.js

Since version 1.1.1 gyp.js uses environment files. Set --target_arch
command-line option with value of node-gyp --arch option in order to
generate proper ninja environment file.

Author: pmed

lib/configure.js

@@ -31,6 +31,7 @@ function configure (gyp, argv, callback) {
     , buildDir = path.resolve('build')
     , configNames = [ 'config.gypi', 'common.gypi' ]
     , configs = []
+    , arch
     , nodeDir
     , release = processRelease(argv, gyp, process.version, process.release)
 
@@ -130,7 +131,7 @@ function configure (gyp, argv, callback) {
     }
 
     // set the target_arch variable
-    variables.target_arch = gyp.opts.arch || process.arch || 'ia32'
+    variables.target_arch = arch = gyp.opts.arch || process.arch || 'ia32'
 
     // set the node development directory
     variables.nodedir = nodeDir
@@ -297,6 +298,7 @@ function configure (gyp, argv, callback) {
         var cp = gyp.spawn(python, argv)
         cp.on('exit', onCpExit)
       } else {
+        argv.push('-Dtarget_arch=' + arch)
         onCpExit(gypjs.main(argv))
       }
     })