Use sys.platform instead of Utils.detect_platform

Utils.detect_platform is no longer available, so let's use the
underlying sys.platform instead. On Linux, sys.platform returns "linux2"
these days, but upstreams is considering to change it "linux" in the
future.

wscript

@@ -10,6 +10,7 @@ import shutil
 import Task
 import re
 import Logs
+import sys
 
 VERSION='1.9.9'
 APPNAME='jack'
@@ -77,9 +78,9 @@ def set_options(opt):
     opt.sub_options('dbus')
 
 def configure(conf):
-    platform = Utils.detect_platform()
+    platform = sys.platform
     conf.env['IS_MACOSX'] = platform == 'darwin'
-    conf.env['IS_LINUX'] = platform == 'linux' or platform == 'posix'
+    conf.env['IS_LINUX'] = platform == 'linux' or platform == 'linux2' or platform == 'posix'
     conf.env['IS_SUN'] = platform == 'sunos'
 
     if conf.env['IS_LINUX']: