refactor: Drop unneeded <sys/types.h> include before <ifaddrs.h>

Pure `getifaddrs()`/`freeifaddrs()` calls do not need any type
definitions beyond those provided by `<ifaddrs.h>` itself.

The subsequent `struct ifaddrs` processing in `netif.cpp` does not
involve any symbols from `<sys/types.h>`.

cmake/module/TestAppendRequiredLibraries.cmake

@@ -15,7 +15,6 @@ function(test_append_socket_library target)
   endif()
 
   set(check_socket_source "
-    #include <sys/types.h>
     #include <ifaddrs.h>
 
     int main() {

src/common/netif.cpp

@@ -30,7 +30,6 @@
 #endif
 
 #ifdef HAVE_IFADDRS
-#include <sys/types.h>
 #include <ifaddrs.h>
 #endif