LU-15838 autoconf: fix use of obsolete macros

LU-15838 autoconf: fix use of obsolete macros

This patch fixes the following warnings when using autoconf 2.71:

configure.ac:2: warning: AC_INIT: not a literal:
                "m4_esyscmd(sh -c "./LUSTRE-VERSION-GEN | tr -d '\n'")"
configure.ac:10: warning: The macro `AC_CANONICAL_SYSTEM' is obsolete.
configure.ac:16: warning: The macro `AC_PROG_LIBTOOL' is obsolete.
configure.ac:24: warning: The macro `AC_HELP_STRING' is obsolete.

Like m4_esyscmd, macro m4_esyscmd_s (introduced in autoconf 2.64)
expands to the result of running command in a shell. The difference
is that any trailing newlines are removed.

Since autoconf 2.50, macro 'AC_CANONICAL_TARGET' has been the new name
of 'AC_CANONICAL_SYSTEM':
AU_ALIAS([AC_CANONICAL_SYSTEM], [AC_CANONICAL_TARGET])

Since autoconf 2.58, macro 'AS_HELP_STRING' has been added to replace
'AC_HELP_STRING'.

Since libtool 2.0, new 'LT_INIT' interface has been added to replace
'AC_PROG_LIBTOOL'.

Change-Id: I3c06c21460d7a2cf643fe825e72a26a5416609cf
Signed-off-by: Jian Yu <yujian@whamcloud.com>