asyn-thread: use c-ares to resolve HTTPS RR

Allow building with c-ares and yet use threaded resolver for the main
host A/AAAA resolving:

  `--with-ares` provides the c-ares install path and defaults to use
  c-ares for name resolving

  `--with-threaded-resolver` still uses c-ares in the build (for HTTPS)
  but uses the threaded resolver for "normal" resolves.

It works similarly for cmake: ENABLE_ARES enables ares, and if
ENABLE_THREADED_RESOLVER also is set, c-ares is used for HTTPS RR and
the threaded resolver for "normal" resolves.

HTTPSRR and c-ares-rr are new features return by curl_version_info() and
thus shown by curl -V.

The c-ares-rr feature bit is there to make it possible to distinguish
between builds using c-ares for all name resolves and builds that use
the threaded resolves for the regular name resolves and c-ares for
HTTPSRR only. "c-ares-rr" means it does not use c-ares for "plain" name
resolves.

HTTPSRR support is EXPERIMENTAL only.

Closes #16054

tests/FILEFORMAT.md

@@ -434,7 +434,8 @@ Features testable here are:
 - `AppleIDN`
 - `bearssl`
 - `brotli`
-- `c-ares`
+- `c-ares` - c-ares is used for (all) name resolves
+- `c-ares-rr` - c-ares is used for additional records only
 - `CharConv`
 - `codeset-utf8`. If the running codeset is UTF-8 capable.
 - `cookies`

tests/data/test1014

@@ -28,7 +28,7 @@ Compare curl --version with curl-config --features
 # Verify data after the test has been "shot"
 <verify>
 <postcheck>
-%SRCDIR/libtest/test1013.pl ../curl-config %LOGDIR/stdout%TESTNUMBER features
+%SRCDIR/libtest/test1013.pl ../curl-config %LOGDIR/stdout%TESTNUMBER features > %LOGDIR/result%TESTNUMBER
 </postcheck>
 <errorcode>
 0

tests/libtest/lib1565.c

@@ -205,6 +205,6 @@ test_cleanup:
 CURLcode test(char *URL)
 {
   (void)URL;
-  return 0;
+  return CURLE_OK;
 }
 #endif

tests/runtests.pl

@@ -698,6 +698,8 @@ sub checksystemfeatures {
             $feature{"Unicode"} = $feat =~ /Unicode/i;
             # Thread-safe init
             $feature{"threadsafe"} = $feat =~ /threadsafe/i;
+            $feature{"HTTPSRR"} = $feat =~ /HTTPSRR/;
+            $feature{"c-ares-rr"} = $feat =~ /c-ares-rr/;
         }
         #
         # Test harness currently uses a non-stunnel server in order to
@@ -822,7 +824,6 @@ sub checksystemfeatures {
     $feature{"large-time"} = 1;
     $feature{"large-size"} = 1;
     $feature{"sha512-256"} = 1;
-    $feature{"HTTPSRR"} = 1;
     $feature{"local-http"} = servers::localhttp();
     $feature{"codeset-utf8"} = lc(langinfo(CODESET())) eq "utf-8";
 

tests/server/disabled.c

@@ -115,9 +115,6 @@ static const char *disabled[]={
 #ifndef CURL_CA_SEARCH_SAFE
   "win32-ca-search-safe",
 #endif
-#endif
-#ifndef USE_HTTPSRR
-  "HTTPSRR",
 #endif
   NULL
 };