mapgdal: remove useless memory allocation

mapgdal.c

@@ -140,7 +140,6 @@ int msSaveImageGDAL( mapObj *map, imageObj *image, const char *filenameIn )
   GDALDriverH  hMemDriver, hOutputDriver;
   int          nBands = 1;
   int          iLine;
-  GByte       *pabyAlphaLine = NULL;
   char        **papszOptions = NULL;
   outputFormatObj *format = image->format;
   rasterBufferObj rb;
@@ -216,12 +215,6 @@ int msSaveImageGDAL( mapObj *map, imageObj *image, const char *filenameIn )
       return MS_FAILURE;
     }
   } else if( format->imagemode == MS_IMAGEMODE_RGBA ) {
-    pabyAlphaLine = (GByte *) calloc(image->width,1);
-    if (pabyAlphaLine == NULL) {
-      msReleaseLock( TLOCK_GDAL );
-      msSetError( MS_MEMERR, "Out of memory allocating %u bytes.\n", "msSaveImageGDAL()", image->width);
-      return MS_FAILURE;
-    }
     nBands = 4;
     assert( MS_RENDERER_PLUGIN(format) && format->vtable->supports_pixel_buffer );
     if(MS_UNLIKELY(MS_FAILURE == format->vtable->getRasterBufferHandle(image,&rb))) {
@@ -359,9 +352,6 @@ int msSaveImageGDAL( mapObj *map, imageObj *image, const char *filenameIn )
     }
   }
 
-  if( pabyAlphaLine != NULL )
-    free( pabyAlphaLine );
-
   /* -------------------------------------------------------------------- */
   /*      Attach the palette if appropriate.                              */
   /* -------------------------------------------------------------------- */