Cleanup: Add files for version independent versioning helpers

Adds `source/blender/blendloader/intern/versioning_common.cc` and
`versioning_common.h` for version independent versioning functions.

I only placed `do_versions_add_region_if_not_found()` in there for now.
`blo_do_version_old_trackto_to_constraints()` could also be added, but
that's so old, I prefer keeping that in `versioning_legacy.c`.

source/blender/blenloader/CMakeLists.txt

@@ -59,6 +59,7 @@ set(SRC
   intern/versioning_290.c
   intern/versioning_300.c
   intern/versioning_cycles.c
+  intern/versioning_common.cc
   intern/versioning_defaults.c
   intern/versioning_dna.c
   intern/versioning_legacy.c
@@ -72,6 +73,7 @@ set(SRC
   BLO_undofile.h
   BLO_writefile.h
   intern/readfile.h
+  intern/versioning_common.h
 )
 
 set(LIB

source/blender/blenloader/intern/versioning_290.c

@@ -80,6 +80,7 @@
 
 #include "BLO_readfile.h"
 #include "readfile.h"
+#include "versioning_common.h"
 
 /* Make preferences read-only, use versioning_userdef.c. */
 #define U (*((const UserDef *)&U))
@@ -861,26 +862,6 @@ static void version_node_join_geometry_for_multi_input_socket(bNodeTree *ntree)
   }
 }
 
-static ARegion *do_versions_add_region_if_not_found(ListBase *regionbase,
-                                                    int region_type,
-                                                    const char *name,
-                                                    int link_after_region_type)
-{
-  ARegion *link_after_region = NULL;
-  LISTBASE_FOREACH (ARegion *, region, regionbase) {
-    if (region->regiontype == region_type) {
-      return NULL;
-    }
-    if (region->regiontype == link_after_region_type) {
-      link_after_region = region;
-    }
-  }
-  ARegion *new_region = MEM_callocN(sizeof(ARegion), name);
-  new_region->regiontype = region_type;
-  BLI_insertlinkafter(regionbase, link_after_region, new_region);
-  return new_region;
-}
-
 /* NOLINTNEXTLINE: readability-function-size */
 void blo_do_versions_290(FileData *fd, Library *UNUSED(lib), Main *bmain)
 {

source/blender/blenloader/intern/versioning_common.cc

@@ -0,0 +1,50 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup blenloader
+ */
+/* allow readfile to use deprecated functionality */
+#define DNA_DEPRECATED_ALLOW
+
+#include "DNA_screen_types.h"
+
+#include "BLI_listbase.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "versioning_common.h"
+
+ARegion *do_versions_add_region_if_not_found(ListBase *regionbase,
+                                             int region_type,
+                                             const char *name,
+                                             int link_after_region_type)
+{
+  ARegion *link_after_region = NULL;
+  LISTBASE_FOREACH (ARegion *, region, regionbase) {
+    if (region->regiontype == region_type) {
+      return NULL;
+    }
+    if (region->regiontype == link_after_region_type) {
+      link_after_region = region;
+    }
+  }
+
+  ARegion *new_region = static_cast<ARegion *>(MEM_callocN(sizeof(ARegion), name));
+  new_region->regiontype = region_type;
+  BLI_insertlinkafter(regionbase, link_after_region, new_region);
+  return new_region;
+}

source/blender/blenloader/intern/versioning_common.h

@@ -0,0 +1,37 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup blenloader
+ */
+
+#pragma once
+
+struct ARegion;
+struct ListBase;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct ARegion *do_versions_add_region_if_not_found(struct ListBase *regionbase,
+                                                    int region_type,
+                                                    const char *name,
+                                                    int link_after_region_type);
+
+#ifdef __cplusplus
+}
+#endif