Bump version to 2.4.9

Who needs 2.4.8 anyway?
diff --git a/configure.ac b/configure.ac
index 5c82dcf..19d9c9c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,8 +18,8 @@
 #  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 #  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-AC_PREREQ(2.58)
-AC_INIT([libdrm], 2.4.7, [dri-devel@lists.sourceforge.net], libdrm)
+AC_PREREQ(2.57)
+AC_INIT([libdrm], 2.4.9, [dri-devel@lists.sourceforge.net], libdrm)
 AC_CONFIG_SRCDIR([Makefile.am])
 AM_INIT_AUTOMAKE([dist-bzip2])