vk/formats: Add global pointer to anv_format for S8_UINT

Stencil formats are often a special case. To reduce the number of lookups
into the VkFormat-to-anv_format translation table when working with
stencil, expose the table's entry for VK_FORMAT_S8_UINT as global
variable anv_format_s8_uint.

src/vulkan/anv_formats.c

@@ -209,6 +209,9 @@ static const struct anv_format anv_formats[] = {
 
 #undef fmt
 
+const struct anv_format *const
+anv_format_s8_uint = &anv_formats[VK_FORMAT_S8_UINT];
+
 const struct anv_format *
 anv_format_for_vk_format(VkFormat format)
 {

src/vulkan/anv_private.h

@@ -879,6 +879,13 @@ struct anv_format {
    bool has_stencil;
 };
 
+/**
+ * Stencil formats are often a special case. To reduce the number of lookups
+ * into the VkFormat-to-anv_format translation table when working with
+ * stencil, here is the handle to the table's entry for VK_FORMAT_S8_UINT.
+ */
+extern const struct anv_format *const anv_format_s8_uint;
+
 const struct anv_format *
 anv_format_for_vk_format(VkFormat format);
 bool anv_is_vk_format_depth_or_stencil(VkFormat format);