Add missing <cassert> includes

Until recently we were probably getting it from some transitive
include, but it broke. Because all files should include what
they use anyway, adding `#include <cassert>` to all files that
use `assert()` without including it is the best solution.

Fixes #1249

include/internal/catch_result_builder.hpp

@@ -16,6 +16,8 @@
 #include "catch_interfaces_registry_hub.h"
 #include "catch_wildcard_pattern.hpp"
 
+#include <cassert>
+
 namespace Catch {
 
     ResultBuilder::ResultBuilder(   char const* macroName,

include/internal/catch_run_context.hpp

@@ -22,7 +22,7 @@
 #include "catch_result_builder.h"
 #include "catch_fatal_condition.hpp"
 
-
+#include <cassert>
 #include <set>
 #include <string>
 

include/reporters/catch_reporter_console.hpp

@@ -13,6 +13,7 @@
 #include "../internal/catch_reporter_registrars.hpp"
 #include "../internal/catch_console_colour.hpp"
 
+#include <cassert>
 #include <cfloat>
 #include <cstdio>
 

include/reporters/catch_reporter_teamcity.hpp

@@ -14,6 +14,7 @@
 // file can be distributed as a single header that works with the main
 // Catch single header.
 
+#include <cassert>
 #include <cstring>
 
 #ifdef __clang__