scons: need to split CC or things might fail

We've seen this fail internally.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>

scons/gallium.py

@@ -134,7 +134,9 @@ def check_cc(env, cc, expr, cpp_opt = '-E'):
     source.write('#if !(%s)\n#error\n#endif\n' % expr)
     source.close()
 
-    pipe = SCons.Action._subproc(env, [env['CC'], cpp_opt, source.name],
+    # sys.stderr.write('%r %s %s\n' % (env['CC'], cpp_opt, source.name));
+
+    pipe = SCons.Action._subproc(env, env.Split(env['CC']) + [cpp_opt, source.name],
                                  stdin = 'devnull',
                                  stderr = 'devnull',
                                  stdout = 'devnull')