Greetings all.

Attached is a patch that adds warning counting logic.  Warnings produced 
by the test suite will be tallied on all platforms, but compiler/linker 
warnings will not be detected on Windows, as the output logs aren't 
generated in the format/location expected by the log parsing code.  This 
is due to the inherent differences between the Windows and UNIX make 
infrastructure.  This likely will be corrected in a follow-up patch.

This patch is a stepping-stone towards generating HTML output from the 
exec utility.

--Andrew Black

Log:
	* makefile.rules (%.o: %(AS_EXT), %.o: %.cpp, %: %.o, %: %.cpp): Add 
$(TEEOPTS) to compile/link line so that output is routed to log files.
	* makefile.common (TEEOPTS): Always tee output to $@.log.
	* target.h (target_opts): Add c_warn and l_warn fields.
	  (target_status): Split warn field into c_warn, l_warn, t_warn.
	* output.cpp (check_test): Count warnings, store in status->t_warn.
	  (check_compat_test): Expand tail horizon, capture warnings into 
status->t_warn.
	* display.cpp (print_header_plain): Add WARN column.
	  (print_status_plain): Print the total number of warnings in the WARN 
column.
	* runall.cpp (count_warnings): Add static method to count the number of 
warnings in a .log file
	  (check_target_ok): Always calculate object file name, call 
count_warnings for object and executable.
	* cmdopt.cpp (usage_text): Document new --warn switch
	  (parse_warn_opts): Define new helper function to parse --warn switch.
	  (eval_options): Used here, initialize default c_warn and l_warn values.