agx: Add sysval management helper

Will be used for lowering UBO loads, among other applications.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10582>

src/asahi/compiler/agx_compiler.h

@@ -542,6 +542,12 @@ agx_builder_insert(agx_cursor *cursor, agx_instr *I)
    unreachable("Invalid cursor option");
 }
 
+/* Uniform file management */
+
+agx_index
+agx_indexed_sysval(agx_context *ctx, enum agx_push_type type, enum agx_size size,
+      unsigned index, unsigned length);
+
 /* Routines defined for AIR */
 
 void agx_print_instr(agx_instr *I, FILE *fp);