[Mesa-stable] [PATCH] configure.ac: Augment error message to list vulkan drivers.

[Bas Nieuwenhuizen]

Had someone that tried --with-vulkan-drivers=radv, this will guide
people in the right direction.

Signed-off-by: Bas Nieuwenhuizen <basni at google.com>
CC: <mesa-stable at lists.freedesktop.org>
---
 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index b35adc8a3aa..166e588ed56 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1774,7 +1774,7 @@ if test -n "$with_vulkan_drivers"; then
             HAVE_RADEON_VULKAN=yes;
             ;;
         *)
-            AC_MSG_ERROR([Vulkan driver '$driver' does not exist])
+            AC_MSG_ERROR([Vulkan driver '$driver' does not exist, valid drivers are 'intel' and 'radeon'])
             ;;
         esac
     done
-- 
2.11.0