Slap u64 on everything time-y

* get_us_time() will overflow and reset to zero every now and then.
  Had it happen several times in one day,
  https://github.com/minetest/minetest/issues/10105
* backported b5eda416ce

builtin/mainmenu/pkgmgr.lua

@@ -51,7 +51,7 @@ function get_mods(path,retval,modpack)
 			-- Read from config
 			toadd.name = name
 			toadd.author = mod_conf.author
-			toadd.release = tonumber(mod_conf.release or "0")
+			toadd.release = tonumber(mod_conf.release or 0)
 			toadd.path = prefix
 			toadd.type = "mod"
 
@@ -99,7 +99,7 @@ function pkgmgr.get_texture_packs()
 			retval[#retval + 1] = {
 				name = item,
 				author = conf:get("author"),
-				release = tonumber(conf:get("release") or "0"),
+				release = tonumber(conf:get("release") or 0),
 				list_name = name,
 				type = "txp",
 				path = path,

src/porting.h

@@ -237,21 +237,21 @@ inline u64 getTimeMs()
 {
 	struct timespec ts;
 	os_get_clock(&ts);
-	return ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
+	return ((u64) ts.tv_sec) * 1000LL + ((u64) ts.tv_nsec) / 1000000LL;
 }
 
 inline u64 getTimeUs()
 {
 	struct timespec ts;
 	os_get_clock(&ts);
-	return ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
+	return ((u64) ts.tv_sec) * 1000000LL + ((u64) ts.tv_nsec) / 1000LL;
 }
 
 inline u64 getTimeNs()
 {
 	struct timespec ts;
 	os_get_clock(&ts);
-	return ts.tv_sec * 1000000000 + ts.tv_nsec;
+	return ((u64) ts.tv_sec) * 1000000000LL + ((u64) ts.tv_nsec);
 }
 
 #endif