Detect infinite backtraces.

Detect infinite backtraces.

libdwfl/
2014-01-03  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Detect infinite backtraces.
	* dwfl_frame.c (state_alloc): Initialize CFA.
	* frame_unwind.c (expr_eval): Remove parameter frame, add parameter
	elfclass.  Move elfclass to handle_cfi.  Replace recursive call by
	state->unwound->CFA.
	(new_unwound): Initialize CFA.
	(handle_cfi): Move elfclass here.  Compute CFA.  Update expr_eval
	caller parameters.
	* libdwflP.h (DWFL_ERRORS): Add UNWIND_BAD_CFA.
	(struct Dwfl_Frame): Add field cfa.

tests/
2014-01-03  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* Makefile.am (TESTS): Add run-cfaloop.sh.
	(EXTRA_DIST): Add run-cfaloop.sh, testfilecfaloop.S,
	testfilecfaloop.bz2, testfilecfaloop.c and testfilecfaloop.core.bz2.
	* run-cfaloop.sh: New file.
	* testfilecfaloop.S: New file.
	* testfilecfaloop.bz2: New file.
	* testfilecfaloop.c: New file.
	* testfilecfaloop.core.bz2: New file.

Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>