Fix some weird code in strrepc of task.c

So little code, so many faults:
* It calls strchr from the beginning each time
  (it could use ++ptr as the start)
* If cFrom and cTo are the same it loops forever
* if int is 32bits && ptr is 64bits it may break
  (many are, and the cast truncates the pointer)
* if sizeof(char) > 1 it breaks badly

trace.c

@@ -191,15 +191,11 @@ static int strrepc(char *pszStr, char cFrom, char cTo)
 
       /*----------------------------------------------------------------*/
 
-      while( 0 != ( ptr = strchr( pszStr, cFrom ) ) )
-
-      {     /* WHILE cFrom occurs in pszStr */
-
-            pszStr[ (int) ptr - (int) pszStr ] = cTo ;
-
-            /*- Replace next cFrom with cTo */
-
-            iReturn++ ;                                           /*- count */
+      for (ptr = pszStr; ptr && *ptr; ++ptr) {
+            if (*ptr == cFrom) {
+              *ptr = cTo;
+              ++iReturn;
+            }
       }
 
       return( iReturn ) ;