made new test case an error test case

--HG--
rename : tests/compile/nonconst_def.pyx => tests/errors/nonconst_def.pyx

tests/compile/nonconst_def.pyx

-import os
-DEF ospath = os.path
-

tests/errors/nonconst_def.pyx

+import os
+DEF ospath = os.path
+
+_ERRORS = u"""
+2:15: Compile-time name 'os' not defined
+2:15: Error in compile-time expression: AttributeError: 'NoneType' object has no attribute 'path'
+"""