llvmpipe: add debug bit for mesh shaders

Reviewed-by: Roland Scheidegger <sroland@vmware.com>#
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23066>

src/gallium/drivers/llvmpipe/lp_debug.h

@@ -52,6 +52,7 @@
 #define DEBUG_LINEAR2       0x200000
 #define DEBUG_SHOW_DEPTH    0x400000
 #define DEBUG_ACCURATE_A0   0x800000 /* verbose */
+#define DEBUG_MESH         0x1000000
 
 /* Performance flags.  These are active even on release builds.
  */

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -81,6 +81,7 @@ static const struct debug_named_value lp_debug_flags[] = {
    { "cs", DEBUG_CS, NULL },
    { "tgsi_ir", DEBUG_TGSI_IR, NULL },
    { "accurate_a0", DEBUG_ACCURATE_A0 },
+   { "mesh", DEBUG_MESH },
    DEBUG_NAMED_VALUE_END
 };