Fix segfaults due to parameter size mismatch

Changes from Karl Williamson:
https://rt.cpan.org/Ticket/Display.html?id=128955

Author: khwilliamson

pTk/mTk/generic/tkCanvText.c

@@ -1234,7 +1234,7 @@ GetTextIndex(interp, canvas, itemPtr, obj, indexPtr)
 				 * index. */
 {
     TextItem *textPtr = (TextItem *) itemPtr;
-    size_t length;
+    int length;
     int c;
     TkCanvas *canvasPtr = (TkCanvas *) canvas;
     Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;

pTk/mTk/generic/tkFrame.c

@@ -494,7 +494,7 @@ CreateFrame(clientData, interp, objc, objv, type, appName)
     Tcl_Obj *visualName;
     Tcl_Obj *useOption;
     int i, c, depth;
-    size_t length;
+    int length;
     unsigned int mask;
     Colormap colormap;
     Visual *visual;
@@ -749,7 +749,7 @@ FrameWidgetObjCmd(clientData, interp, objc, objv)
     };
     register Frame *framePtr = (Frame *) clientData;
     int result = TCL_OK, index;
-    size_t length;
+    int length;
     int c, i;
     Tcl_Obj *objPtr;