scons: make embedding orthogonal to the platform

To enable embedding in platforms other than linux.
diff --git a/common.py b/common.py
index 0a3dcdc..052929e 100644
--- a/common.py
+++ b/common.py
@@ -83,7 +83,8 @@
 	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', 'cell', 'windows', 'winddk', 'wince', 'darwin', 'embedded', 'cygwin', 'sunos', 'freebsd8')))
+											 allowed_values=('linux', 'cell', 'windows', 'winddk', 'wince', 'darwin', 'cygwin', 'sunos', 'freebsd8')))
+	opts.Add(BoolOption('embedded', 'embedded build', 'no'))
 	opts.Add('toolchain', 'compiler toolchain', default_toolchain)
 	opts.Add(BoolOption('gles', 'EXPERIMENTAL: enable OpenGL ES support', 'no'))
 	opts.Add(BoolOption('llvm', 'use LLVM', default_llvm))