meson: install vulkan_intel.h header

Fixes: d1992255bb29054fa51763376d125183a9f602f3
       ("meson: Add build Intel "anv" vulkan driver")
Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/include/meson.build b/include/meson.build
index 28ffb33..b4555ea 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -106,3 +106,7 @@
     subdir: 'CL'
   )
 endif
+
+if with_intel_vk
+  install_headers('vulkan/vulkan_intel.h', subdir : 'vulkan')
+endif