tests: add 'large-time' as a testable feature

This allows test cases to require this feature to run and to be used in
%if conditions.

Large here means larger than 32 bits. Ie does not suffer from y2038.

Closes #11696

tests/FILEFORMAT.md

@@ -428,6 +428,7 @@ Features testable here are:
 - `ipv6`
 - `Kerberos`
 - `large_file`
+- `large-time` (time_t is larger than 32 bit)
 - `ld_preload`
 - `libssh2`
 - `libssh`

tests/runtests.pl

@@ -793,6 +793,7 @@ sub checksystemfeatures {
     $feature{"wakeup"} = 1;
     $feature{"headers-api"} = 1;
     $feature{"xattr"} = 1;
+    $feature{"large-time"} = 1;
 
     # make each protocol an enabled "feature"
     for my $p (@protocols) {

tests/server/disabled.c

@@ -84,6 +84,9 @@ static const char *disabled[]={
 #endif
 #ifdef CURL_DISABLE_FORM_API
   "form-api",
+#endif
+#if (SIZEOF_TIME_T < 5)
+  "large-time",
 #endif
   NULL
 };