Add --enable-hardening which builds e2fsprogs with security hardening

Add --enable-hardening which builds e2fsprogs with security hardening

Enable the following security features: stack protection, fortify,
read-only relocation tables, immediate dynamic symbol binding, and
text segment ASLR by enabling position independent executable
(PIE).

Special handling is provided for shared library and statically linked
executables.  For all the gory details please see:

   https://lists.debian.org/debian-devel/2016/05/msg00302.html

Distributions who want to do their own special thing can set CFLAGS,
CFLAGS_SHLIB, CLFAGS_STLIB, LDFLAGS, LDFLAGS_SHLIB and LDFLAGS_STATIC
as appropriate.

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