coverage.c: Refer to "notes file" instead of "graph file" in all comments.

coverage.c: Refer to "notes file" instead of "graph file" in all comments.

gcc/
	* coverage.c: Refer to "notes file" instead of "graph file"
	in all comments.  Explain history of bbg prefix.
	* gcov-io.h: Likewise.
	* gcov.c: Likewise.
	(find_source): Likewise in fnotice.
	(read_graph_file): Likewise.
	(read_count_file): Likewise.
	* doc/gcov.texi: Document -fprofile-dir flag.  Add "notes file"
	and "data file" explicitly in the explanation of the files.

libgcc/
	* libgcov.c (__gcov_ior_profiler): Benign comment fix.

From-SVN: r189781