runtests: make 'wolfssl' a testable feature

Closes #8252

tests/FILEFORMAT.md

@@ -422,6 +422,7 @@ Features testable here are:
 - `wakeup`
 - `win32`
 - `wolfssh`
+- `wolfssl`
 
 as well as each protocol that curl supports.  A protocol only needs to be
 specified if it is different from the server (useful when the server

tests/runtests.pl

@@ -2883,6 +2883,7 @@ sub setupfeatures {
     $feature{"libssh"} = $has_libssh;
     $feature{"rustls"} = $has_rustls;
     $feature{"wolfssh"} = $has_wolfssh;
+    $feature{"wolfssl"} = $has_wolfssl;
     $feature{"manual"} = $has_manual;
     $feature{"MinGW"} = $has_mingw;
     $feature{"MultiSSL"} = $has_multissl;