Fix #637, static module unload fix

Mark static modules with a flag, and check that flag at unload.
If flag is set, then skip unload low level implementation.

src/os/shared/inc/os-shared-module.h

@@ -30,6 +30,8 @@
 
 #include <os-shared-globaldefs.h>
 
+#define OS_MODULE_FLAG_IS_STATIC        0x1
+
 typedef struct
 {
     char    module_name[OS_MAX_API_NAME];

src/os/shared/src/osapi-module.c

@@ -232,7 +232,12 @@ int32 OS_ModuleLoad(osal_id_t *module_id, const char *module_name, const char *f
          * returns OS_ERR_NAME_NOT_FOUND.
          */
         return_code = OS_ModuleLoad_Static(module_name);
-        if (return_code != OS_SUCCESS)
+        if (return_code == OS_SUCCESS)
+        {
+            /* mark this as a statically loaded module */
+            OS_module_table[local_id].flags |= OS_MODULE_FLAG_IS_STATIC;
+        }
+        else
         {
             /*
              * If this is NOT a static module, then the module file must be loaded by normal
@@ -280,9 +285,14 @@ int32 OS_ModuleUnload(osal_id_t module_id)
     if (return_code == OS_SUCCESS)
     {
         /*
-         * Only call the implementation if the loader is enabled
+         * Only call the implementation if the file was actually loaded.
+         * If this is a static module, then this is just a placeholder and
+         * it means there was no file actually loaded.
          */
-        return_code = OS_ModuleUnload_Impl(local_id);
+        if ((OS_module_table[local_id].flags & OS_MODULE_FLAG_IS_STATIC) == 0)
+        {
+            return_code = OS_ModuleUnload_Impl(local_id);
+        }
 
         /* Complete the operation via the common routine */
         return_code = OS_ObjectIdFinalizeDelete(return_code, record);