Introduce stubs for throwing specific exception types

This allows us to move <stdexcept> out of the common path, and replace
it with just <exception>. The difference between these two headers is
~13k lines after preprocessing on libstdc++ (16k vs 3k) and ~17k lines
for MS's STL(33k vs 16k).

Note that this is only beneficial if no other stdlib header we use
includes <stdexcept>. AFAIK this is true for the newest MS's STL,
but I have no idea of the applicability for libstdc++ and libc++.

include/internal/catch_enforce.cpp

@@ -7,6 +7,9 @@
 
 #include "catch_enforce.h"
 
+#include <stdexcept>
+
+
 namespace Catch {
 #if defined(CATCH_CONFIG_DISABLE_EXCEPTIONS) && !defined(CATCH_CONFIG_DISABLE_EXCEPTIONS_CUSTOM_HANDLER)
     [[noreturn]]
@@ -16,4 +19,22 @@ namespace Catch {
         std::terminate();
     }
 #endif
+
+    [[noreturn]]
+    void throw_logic_error(std::string const& msg) {
+        throw_exception(std::logic_error(msg));
+    }
+
+    [[noreturn]]
+    void throw_domain_error(std::string const& msg) {
+        throw_exception(std::domain_error(msg));
+    }
+
+    [[noreturn]]
+    void throw_runtime_error(std::string const& msg) {
+        throw_exception(std::runtime_error(msg));
+    }
+
+
+
 } // namespace Catch;