anv: install the intel_icd.json to ${datarootdir} by default

As mentioned by the spec (and used by Archlinux and Debian) default to
${datarootdir} as opposed to ${sysconfdir} for the default location.

Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/configure.ac b/configure.ac
index 3d32c53..c2525d3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1640,7 +1640,7 @@
     [AS_HELP_STRING([--with-vulkan-icddir=DIR],
         [directory for the Vulkan driver icd files @<:@${sysconfdir}/vulkan/icd.d@:>@])],
     [VULKAN_ICD_INSTALL_DIR="$withval"],
-    [VULKAN_ICD_INSTALL_DIR='${sysconfdir}/vulkan/icd.d'])
+    [VULKAN_ICD_INSTALL_DIR='${datarootdir}/vulkan/icd.d'])
 AC_SUBST([VULKAN_ICD_INSTALL_DIR])
 
 if test -n "$with_vulkan_drivers"; then