gallium: add PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT

Reviewed-by: Brian Paul <brianp@vmware.com>

src/gallium/docs/source/screen.rst

@@ -134,6 +134,9 @@ The integer capabilities:
   expected for a pointer returned by transfer_map if the resource is
   PIPE_BUFFER. In other words, the pointer returned by transfer_map is
   always aligned to this value.
+* ``PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT``: Describes the required
+  alignment for pipe_sampler_view::u.buf.first_element, in bytes.
+  If a driver does not support first/last_element, it should return 0.
 
 
 .. _pipe_capf:

src/gallium/include/pipe/p_defines.h

@@ -497,7 +497,8 @@ enum pipe_cap {
    PIPE_CAP_TEXTURE_MULTISAMPLE = 74,
    PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT = 75,
    PIPE_CAP_CUBE_MAP_ARRAY = 76,
-   PIPE_CAP_TEXTURE_BUFFER_OBJECTS = 77
+   PIPE_CAP_TEXTURE_BUFFER_OBJECTS = 77,
+   PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT = 78
 };
 
 /**