vo_gpu: shaderc: include debug info when --gpu-debug is set

This adds symbol information to the generated SPIR-V, which shows up in
the SPIR-V assembly dump. It's also useful for potential RA backends
that use SPIRV-Cross, since the symbol information is used in the
generated shader source.

video/out/gpu/spirv_shaderc.c

@@ -33,6 +33,8 @@ static bool shaderc_init(struct ra_ctx *ctx)
 
     shaderc_compile_options_set_optimization_level(p->opts,
                                             shaderc_optimization_level_size);
+    if (ctx->opts.debug)
+        shaderc_compile_options_set_generate_debug_info(p->opts);
 
     int ver, rev;
     shaderc_get_spv_version(&ver, &rev);