CXX-1167 Fix broken SSL testing

The unit tests to confirm that a pool could be configured with SSL
options never ran because the tests were guarded by a private definition
that was never included. This also concealed a bug where mocking failed
because the necessary private header wasn't included in a test helper header.

This commit adds the private header to the test helper header to fix
mocking and runs the SSL pool configuration test unconditionally if
MONGOC_ENABLE_SSL is configured.  I manually verified that this commit
would have caught the original CXX-1163 bug.

Backported from CXX-1163.

Author: xdg

src/mongocxx/test/pool.cpp

@@ -58,7 +58,7 @@ TEST_CASE("a pool is created with the correct MongoDB URI", "[pool]") {
     REQUIRE(destroy_called);
 }
 
-#if defined(MONGOCXX_ENABLE_SSL) && defined(MONGOC_ENABLE_SSL)
+#if defined(MONGOC_ENABLE_SSL)
 TEST_CASE(
     "If we pass an engaged SSL options struct to the pool class, we will use it to configure the "
     "underlying mongoc pool",

src/third_party/catch/include/helpers.hpp

@@ -15,6 +15,7 @@
 #pragma once
 
 #include <mongocxx/private/libmongoc.hh>
+#include <mongocxx/config/private/prelude.hh>
 
 #define CHECK_OPTIONAL_ARGUMENT(OBJECT, NAME, VALUE) \
     SECTION("has NAME disengaged") {                 \
@@ -229,3 +230,5 @@
         libmongoc::read_prefs_set_max_staleness_seconds.create_instance();       \
     auto read_prefs_set_mode = libmongoc::read_prefs_set_mode.create_instance(); \
     auto read_prefs_set_tags = libmongoc::read_prefs_set_tags.create_instance();
+
+#include <mongocxx/config/private/postlude.hh>