Fix windows build

Utilities have been moved to util/, but includes had not been updated
in Windows-specific files.

Ref: dfd0707a29

app/src/sys/win/command.c

@@ -1,8 +1,8 @@
 #include "command.h"
 
 #include "config.h"
-#include "log.h"
-#include "str_util.h"
+#include "util/log.h"
+#include "util/str_util.h"
 
 static int
 build_cmd(char *cmd, size_t len, const char *const argv[]) {

app/src/sys/win/net.c

@@ -1,7 +1,7 @@
-#include "net.h"
+#include "util/net.h"
 
 #include "config.h"
-#include "log.h"
+#include "util/log.h"
 
 bool
 net_init(void) {