tests: always make bundles, adapt build and tests

Make test bundles the default. Drop non-bundle build mode.
Also do all the optimizations and tidy-ups this allows, simpler builds,
less bundle exceptions, streamlined build mechanics.

Also rework the init/deinit macro magic for unit tests. The new method
allows using unique init/deinit function names, and calling them with
arguments. This is in turn makes it possible to reduce the use of global
variables.

Note this drop existing build options `-DCURL_TEST_BUNDLES=` from cmake
and `--enable-test-bundles` / `--disable-test-bundles` from autotools.

Also:
- rename test entry functions to have unique names: `test_<testname>`
  This removes the last exception that was handled in the generator.
- fix `make dist` to not miss test sources with test bundles enabled.
- sync and merge `tests/mk-bundle.pl` into `scripts/mk-unity.pl`.
- mk-unity.pl: add `--embed` option and use it when `CURL_CLANG_TIDY=ON`
  to ensure that `clang-tidy` does not miss external test C sources.
  (because `clang-tidy` ignores code that's #included.)
- tests/unit: drop no-op setup/stop functions.
- tests: reduce symbol scopes, global macros, other fixes and tidy-ups.
- tool1621: fix to run, also fix it to pass.
- sockfilt: fix Windows compiler warning in certain unity include order,
  by explicitly including `warnless.h`.

Follow-up to 6897aeb105 #17468

Closes #17590

tests/unit/unit1661.c

@@ -25,8 +25,6 @@
 #include "bufref.h"
 #include "memdebug.h"
 
-static struct bufref bufref;
-
 static int freecount = 0;
 
 static void test_free(void *p)
@@ -36,19 +34,23 @@ static void test_free(void *p)
   free(p);
 }
 
-static CURLcode unit_setup(void)
+static CURLcode t1661_setup(struct bufref *bufref)
 {
-  Curl_bufref_init(&bufref);
+  Curl_bufref_init(bufref);
   return CURLE_OK;
 }
 
-static void unit_stop(void)
+static void t1661_stop(struct bufref *bufref)
 {
-  Curl_bufref_free(&bufref);
+  Curl_bufref_free(bufref);
 }
 
-UNITTEST_START
+static CURLcode test_unit1661(char *arg)
 {
+  struct bufref bufref;
+
+  UNITTEST_BEGIN(t1661_setup(&bufref))
+
   const char *buffer = NULL;
   CURLcode result = CURLE_OK;
 
@@ -59,7 +61,6 @@ UNITTEST_START
    * 2: reference will be NULL
    * 3: destructor will be NULL
    */
-
   fail_unless(!bufref.ptr, "Initial reference must be NULL");
   fail_unless(!bufref.len, "Initial length must be NULL");
   fail_unless(!bufref.dtor, "Destructor must be NULL");
@@ -67,7 +68,6 @@ UNITTEST_START
   /**
    * testing Curl_bufref_set
    */
-
   buffer = malloc(13);
   abort_unless(buffer, "Out of memory");
   Curl_bufref_set(&bufref, buffer, 13, test_free);
@@ -79,20 +79,17 @@ UNITTEST_START
   /**
    * testing Curl_bufref_ptr
    */
-
   fail_unless((const char *) Curl_bufref_ptr(&bufref) == buffer,
               "Wrong pointer value returned");
 
   /**
    * testing Curl_bufref_len
    */
-
   fail_unless(Curl_bufref_len(&bufref) == 13, "Wrong data size returned");
 
   /**
    * testing Curl_bufref_memdup
    */
-
   result = Curl_bufref_memdup(&bufref, "1661", 3);
   abort_unless(result == CURLE_OK, curl_easy_strerror(result));
   fail_unless(freecount == 1, "Destructor not called");
@@ -108,11 +105,11 @@ UNITTEST_START
   /**
    * testing Curl_bufref_free
    */
-
   Curl_bufref_free(&bufref);
   fail_unless(freecount == 1, "Wrong destructor called");
   fail_unless(!bufref.ptr, "Initial reference must be NULL");
   fail_unless(!bufref.len, "Initial length must be NULL");
   fail_unless(!bufref.dtor, "Destructor must be NULL");
+
+  UNITTEST_END(t1661_stop(&bufref))
 }
-UNITTEST_STOP