gallium/pb: remove 8 bytes from pb_buffer by packing variables

Only svga used usages beyond 16 bits. All other drivers are OK with 16 bits.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9809>

src/gallium/auxiliary/pipebuffer/pb_buffer.h

@@ -112,24 +112,23 @@ struct pb_buffer
 {
    struct pipe_reference  reference;
 
+   /* For internal driver use. It's here so as not to waste space due to
+    * type alignment. (pahole)
+    */
+   uint8_t                placement;
+
    /* Alignments are powers of two, so store only the bit position.
     *    alignment_log2 = util_logbase2(alignment);
     *    alignment = 1 << alignment_log2;
     */
    uint8_t                alignment_log2;
 
-   pb_size                size;
-
    /**
     * Used with pb_usage_flags or driver-specific flags, depending on drivers.
     */
-   unsigned               usage;
+   uint16_t               usage;
 
-   /**
-    * For internal driver use. It's here so as not to waste space due to
-    * type alignment. (pahole)
-    */
-   unsigned               placement;
+   pb_size                size;
 
    /**
     * Pointer to the virtual function table.

src/gallium/winsys/svga/drm/vmw_buffer.h

@@ -34,8 +34,8 @@
 
 
 /* These extra flags are used wherever the pb_usage_flags enum type is used */
-#define VMW_BUFFER_USAGE_SHARED    (1 << 20)
-#define VMW_BUFFER_USAGE_SYNC      (1 << 21)
+#define VMW_BUFFER_USAGE_SHARED    (1 << 14)
+#define VMW_BUFFER_USAGE_SYNC      (1 << 15)
 
 struct SVGAGuestPtr;
 struct pb_buffer;