Vulkan: Fix fprintf format-security warning (#14770)

Author: 0cc4m

ggml/src/ggml-vulkan/vulkan-shaders/vulkan-shaders-gen.cpp

@@ -765,8 +765,8 @@ void write_output_files() {
                 len += "};\n";
             }
         }
-        fprintf(src, data.c_str());
-        fprintf(src, len.c_str());
+        fputs(data.c_str(), src);
+        fputs(len.c_str(), src);
     }
     fclose(hdr);
     fclose(src);