[build1k] Create differ build folder for cross target platforms

rules:
- host target: build_${buildArch}
- cross target: build_${buildTarget}_{buildArch}

1k/build1k.ps1

@@ -878,7 +878,12 @@ if (!$options.setupOnly) {
         $CONFIG_ALL_OPTIONS += $xopts
     }
     if ("$($xopts)".IndexOf('-B') -eq -1) {
+        $is_host_target = ($BUILD_TARGET -eq 'win32') -or ($BUILD_TARGET -eq 'linux') -or ($BUILD_TARGET -eq 'osx')
+        if ($is_host_target) { # wheither building host target?
             $BUILD_DIR = "build_$($options.a)"
+        } else {
+            $BUILD_DIR = "build_${BUILD_TARGET}_$($options.a)"
+        }
     }
     else {
         foreach ($opt in $xopts) {