util: split out some stuff into a new file limits-util.[ch]

src/basic/limits-util.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include <inttypes.h>
+
+uint64_t physical_memory(void);
+uint64_t physical_memory_scale(uint64_t v, uint64_t max);
+
+uint64_t system_tasks_max(void);
+uint64_t system_tasks_max_scale(uint64_t v, uint64_t max);