i965: Add a dependency on libisl

To avoid build issues, ensure that you're running `make' at the top level
and/or you've executed `make clean' beforehand.

Reviewed-by: Chad Versace <chad.versace@intel.com>
diff --git a/configure.ac b/configure.ac
index 9226a0d..e4ce8fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2459,7 +2459,8 @@
 
 AM_CONDITIONAL(HAVE_INTEL_VULKAN, test "x$HAVE_INTEL_VULKAN" = xyes)
 
-AM_CONDITIONAL(HAVE_INTEL_DRIVERS, test "x$HAVE_INTEL_VULKAN" = xyes)
+AM_CONDITIONAL(HAVE_INTEL_DRIVERS, test "x$HAVE_INTEL_VULKAN" = xyes -o \
+                                        "x$HAVE_I965_DRI" = xyes)
 
 AM_CONDITIONAL(NEED_RADEON_DRM_WINSYS, test "x$HAVE_GALLIUM_R300" = xyes -o \
                                             "x$HAVE_GALLIUM_R600" = xyes -o \