0x80000001 can't fit into (signed) long

As far as I can say, this value and all those negative values
are actually not valid in CGM anyway, but since I do not know
the code, I'm leaving them in, they shouldn't break anything.

filter/source/graphicfilter/icgm/bitmap.cxx

@@ -256,7 +256,7 @@ sal_Bool CGMBitmap::ImplGetDimensions( CGMBitmapDescriptor& rDesc )
     rDesc.mnScanSize = 0;
     switch( rDesc.mnLocalColorPrecision )
     {
-        case 0x80000001 :                       // monochrome ( bit = 0->backgroundcolor )
+        case long(0x80000001) :                 // monochrome ( bit = 0->backgroundcolor )
         case 0 :                                //              bit = 1->fillcolor
             rDesc.mnDstBitsPerPixel = 1;
             break;