Add coverage testing using gcov

To check the coverage of e2fsprogs's regression test, do the
following:

	configure --enable-gcov
	make -j8 ; make -j8 check ; make coverage.txt

The coverage information will be the coverage.txt and *.gcov files in
the build directories.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
15 files changed