Clears autoconf warnings such as:
configure.ac:8: warning: The macro `AC_PROG_LIBTOOL' is obsolete. configure.ac:8: You should run autoupdate. m4/libtool.m4:100: AC_PROG_LIBTOOL is expanded from... m4/xcb_util_common.m4:8: XCB_UTIL_COMMON is expanded from... configure.ac:8: the top level
AC_PROG_LIBTOOL was replaced by LT_INIT in libtool 2 in 2008, so it's time to rely on it.
Signed-off-by: Alan Coopersmith firstname.lastname@example.org