vulkan: disable spirv-opt for coopmat shaders (#10763)

There are some bugs in the 1.3.296 SDK, so disable this. It isn't strictly
necessary anyway.

Add missing dependency on vulkan-shaders-gen, so shaders get recompiled when it
changes.

Fix coopmat support reporting when glslc doesn't support NV_coopmat2.

ggml/src/ggml-vulkan/ggml-vulkan.cpp

@@ -2425,9 +2425,11 @@ static void ggml_vk_print_gpu_info(size_t idx) {
         } else if (strcmp("VK_KHR_cooperative_matrix", properties.extensionName) == 0 &&
                    !getenv("GGML_VK_DISABLE_COOPMAT")) {
             coopmat_support = true;
+#if defined(GGML_VULKAN_COOPMAT2_GLSLC_SUPPORT)
         } else if (strcmp("VK_NV_cooperative_matrix2", properties.extensionName) == 0 &&
                    !getenv("GGML_VK_DISABLE_COOPMAT2")) {
             coopmat2_support = true;
+#endif
         }
     }