win: use msbuild from the configure stage

If node-gyp configure has set up MSBuild location use it instead the
one that happens to be first on the PATH.

PR-URL: #1654
Fixes: #1653
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: João Reis <reis@janeasystems.com>

lib/build.js

@@ -95,6 +95,13 @@ function build (gyp, argv, callback) {
    */
 
   function doWhich () {
+    // On Windows use msbuild provided by node-gyp configure
+    if (win && config.variables.msbuild_path) {
+      command = config.variables.msbuild_path
+      log.verbose('using MSBuild:', command)
+      doBuild()
+      return
+    }
     // First make sure we have the build command in the PATH
     which(command, function (err, execPath) {
       if (err) {
@@ -117,13 +124,6 @@ function build (gyp, argv, callback) {
    */
 
   function findMsbuild () {
-    if (config.variables.msbuild_path) {
-      command = config.variables.msbuild_path
-      log.verbose('using MSBuild:', command)
-      doBuild()
-      return
-    }
-
     log.verbose('could not find "msbuild.exe" in PATH - finding location in registry')
     var notfoundErr = 'Can\'t find "msbuild.exe". Do you have Microsoft Visual Studio C++ 2008+ installed?'
     var cmd = 'reg query "HKLM\\Software\\Microsoft\\MSBuild\\ToolsVersions" /s'