Replace hardcoded -ldl with check for availability

2013-05-17  Pavel Chupin  <pavel.v.chupin@intel.com>

	* acinclude.m4: Add check for dlopen in libdl.
	* configure.ac: Ditto.
	* configure: Regenerate.
	* python/py-inferior.c (infpy_read_memory): Don't call
	PyErr_SetString if PyObject_New fails.
	* python/py-frame.c (frame_info_to_frame_object): Don't call
	PyErr_SetString if PyObject_New fails.