scons: Fix SCons build infrastructure for FreeBSD.

This patch gets the FreeBSD SCons build working again. The build still
fails though.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Brian Paul <brianp@vmware.com>
diff --git a/common.py b/common.py
index f0b1ccc..6121a41 100644
--- a/common.py
+++ b/common.py
@@ -89,7 +89,7 @@
 	opts.Add(EnumOption('machine', 'use machine-specific assembly code', default_machine,
 											 allowed_values=('generic', 'ppc', 'x86', 'x86_64')))
 	opts.Add(EnumOption('platform', 'target platform', host_platform,
-											 allowed_values=('linux', 'windows', 'darwin', 'cygwin', 'sunos', 'freebsd8', 'haiku')))
+											 allowed_values=('cygwin', 'darwin', 'freebsd', 'haiku', 'linux', 'sunos', 'windows')))
 	opts.Add(BoolOption('embedded', 'embedded build', 'no'))
 	opts.Add('toolchain', 'compiler toolchain', default_toolchain)
 	opts.Add(BoolOption('gles', 'EXPERIMENTAL: enable OpenGL ES support', 'no'))