libext2fs: Export the library include path.

When adding 'libext2fs' as a library dependency from any other binary,
the binary needs to find the library headers. Users of this library
should not hard-code the include path themselves. This patch exports the
library headers on all three version of the libext2fs library and
removes the redundant include path from executables in e2fsprogs.

Bug: b/23084776
TEST=mma

Change-Id: Idfbfcd2b671a9cddd08c322bc916a5efcc3cffe1
(cherry picked from commit 941ca9e47429b8e0ee86b7b72ca0a107ddc09d22)
3 files changed