Fix build with GCC 16

Signed-off-by: Alec Ari <neotheuser@ymail.com>

Author: NTULINUX

src/rtapi/uspace_rtapi_app.cc

@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
 
 std::atomic_int WithRoot::level;
 uid_t WithRoot::ruid, WithRoot::euid;
@@ -285,4 +286,4 @@ void RtapiApp::set_namef(const char *fmt, ...) {
         fprintf(stderr, "pthread_setname_np() failed for %s: %d\n", buf, res);
     }
     free(buf);
-}
+}