Cleanup: quiet sign-conversion warning in OFFSETOF_STRUCT_AFTER

BLI_strict_flags.h raised a build error when this macro was used.

source/blender/blenlib/BLI_utildefines.h

@@ -589,7 +589,7 @@ extern "C" {
 
 /** Performs `offsetof(typeof(data), member) + sizeof((data)->member)` for non-gcc compilers. */
 #define OFFSETOF_STRUCT_AFTER(_struct, _member) \
-  ((((const char *)&((_struct)->_member)) - ((const char *)(_struct))) + \
+  ((size_t)(((const char *)&((_struct)->_member)) - ((const char *)(_struct))) + \
    sizeof((_struct)->_member))
 
 /**

source/blender/modifiers/intern/MOD_correctivesmooth.c

@@ -52,6 +52,8 @@
 
 #endif
 
+#include "BLI_strict_flags.h"
+
 static void initData(ModifierData *md)
 {
   CorrectiveSmoothModifierData *csmd = (CorrectiveSmoothModifierData *)md;
@@ -63,8 +65,6 @@ static void initData(ModifierData *md)
   csmd->delta_cache.deltas = NULL;
 }
 
-#include "BLI_strict_flags.h"
-
 static void copyData(const ModifierData *md, ModifierData *target, const int flag)
 {
   const CorrectiveSmoothModifierData *csmd = (const CorrectiveSmoothModifierData *)md;

source/blender/modifiers/intern/MOD_screw.c

@@ -41,6 +41,8 @@
 #include "MOD_modifiertypes.h"
 #include "MOD_ui_common.h"
 
+#include "BLI_strict_flags.h"
+
 static void initData(ModifierData *md)
 {
   ScrewModifierData *ltmd = (ScrewModifierData *)md;
@@ -50,8 +52,6 @@ static void initData(ModifierData *md)
   MEMCPY_STRUCT_AFTER(ltmd, DNA_struct_default_get(ScrewModifierData), modifier);
 }
 
-#include "BLI_strict_flags.h"
-
 /** Used for gathering edge connectivity. */
 typedef struct ScrewVertConnect {
   /** Distance from the center axis. */