configure: Build hashtable for Xres and glvnd

With autoconf, hashtable support is built along with Xres support.

Yet, glvnd also use it, so when disabling Xres from configure, the
build will fail at link time because hashtable functions are not
available.

Untie the build of hashtable from Xres support, just like meson build
does.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Closes: xorg/xserver#1091
(cherry picked from commit 899cebb7)
3 jobs for server-1.20-backports in 6 minutes and 6 seconds (queued for 1 second)
Status Job ID Name Coverage
  Docker Image
passed #5470766
debian-testing

00:00:21

 
  Build And Test
passed #5470767
autotools-build-and-test

00:05:45

passed #5470768
meson-build-and-test

00:01:28