Fix build errors in server.c

[embhorn]

Fixes build errors when wolfSSL is configured with --enable-all

src/server/server.c: In function ‘server_test’:
src/server/server.c:2229:28: error: returning ‘int’ from a function with return type ‘THREAD_RETURN’ {aka ‘void *’} makes pointer from integer without a cast [-Werror=int-conversion]
 2229 |                     return BAD_FUNC_ARG;
      |                            ^~~~~~~~~~~~
src/server/server.c:3430:9: error: this ‘if’ clause does not guard... [-Werror=misleading-indentation]
 3430 |         if (ret != WOLFSSL_SUCCESS)
      |         ^~
src/server/server.c:3432:13: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
 3432 |             ((func_args*)args)->return_code = ret;
      |             ^