module: make NEED_MODULE self contained again

register_<Module> is extern "C" so C and D hosts can call it unmangled
between das_initialize_modules() and das_initialize_finalize(). Two side
effects of that linkage broke every C++ host that pulls modules.

The macro can no longer declare the entry point: it expands inside a function
body, a linkage specification is only valid at namespace scope, and declaring
it without one names a different, C++ mangled symbol that nothing defines. So
each host had to add a file scope DECLARE_MODULE per module, boilerplate the
macro already has the name for. REGISTER_MODULE and
REGISTER_MODULE_IN_NAMESPACE now also emit das_pull_<Module>, a C++ linkage
tail call to register_<Module>, and NEED_MODULE declares that instead, which
at block scope is both legal and correct.

The macro also stopped ending in a semicolon, so two bare uses on consecutive
lines spliced into one expression and the second leading * became a
multiplication:

    error: invalid operands to binary expression ('unsigned int' and
           'DasThreadLocal<unsigned int, ...>')

Put the semicolon back. A call site that writes its own gets an empty
statement.

Pulling a module from C++ needs no declaration again:

    void pull_game_das() {
        NEED_MODULE(SomeModule)
    }

The C side is untouched: register_<Module> and jit_register_<Module> keep C
linkage and their unmangled names, so the C API embedding flow works exactly
as documented. DECLARE_MODULE and PULL_MODULE keep working for callers that
would rather declare at file scope.

Author: aleksisch

include/daScript/ast/ast.h

@@ -1303,6 +1303,9 @@ namespace das
         } \
         extern "C" DAS_EXPORT_DLL das::Module * jit_register_##ClassName () { \
             return register_##ClassName(); \
+        } \
+        DAS_EXPORT_DLL das::Module * das_pull_##ClassName () { \
+            return register_##ClassName(); \
         }
 
     #if DAS_ENABLE_DLL
@@ -1333,6 +1336,9 @@ namespace das
         } \
         extern "C" DAS_EXPORT_DLL das::Module * jit_register_##ClassName () { \
             return register_##ClassName(); \
+        } \
+        DAS_EXPORT_DLL das::Module * das_pull_##ClassName () { \
+            return register_##ClassName(); \
         }
 
     using module_pull_t = das::Module*(*)();

include/daScript/daScriptModule.h

@@ -46,7 +46,8 @@ DAS_CC_API void register_fusion ();
 // modules are declared above. A separately compiled custom module must first be
 // declared with DECLARE_MODULE at file scope.
 #define NEED_MODULE(ClassName) \
-    *das::ModuleKarma += unsigned(intptr_t(::register_##ClassName()))
+    extern DAS_API das::Module * das_pull_##ClassName (); \
+    *das::ModuleKarma += unsigned(intptr_t(das_pull_##ClassName()));
 
 #define NEED_FUSION \
     ::register_fusion()