Adjust test/stressGraphics.ref

One of the tests fails with just a few bytes on latest Fedora
releases. Failures can be seen for both test-stressgraphics and
test-stressgraphics-interpreted. Failures are reported for sizes being
201, 202 or 203 bytes larger than the reference, with thw limit
currently set to 200 bytes.

Test 19: TGaxis 3 (Time on axis)................................... OK
         PDF output......................................... 19 FAILED
         Result    = 42723
         Reference = 42926
         Error     = 203 (was 200)
         JPG output................................................ OK
         PNG output................................................ OK
         C file result............................................. OK

Author: ellert

test/stressGraphics.ref

@@ -17,7 +17,7 @@ Test#   PS1Ref#   PS1Err#   PDFRef#   PDFErr#   JPGRef#   JPGErr#   PNGRef#   PN
    16     28072       400     23287       200     44462     11000     30062      5000     38007       400
    17     20444       400     21520       150     27511     11000     16867       600     20721       400
    18     15894       100     19305       200     27187     10300     15925       350     15925       100
-   19     22521       300     42926       200     43868     17000     19232     11000     22729       300
+   19     22521       300     42926       250     43868     17000     19232     11000     22729       300
    20      3664       600     14437       150     19824      6300     10396       900      4220       600
    21     17608       600     13900       150     49440      6300     37586      9000      8938       600
    22      5086       600     14193       150     16812      6300     11900      9000      5156       600