fix test suite thresholds

changes in jpg encode/decode mean we must adjust test suite thresholds

ChangeLog

@@ -2,6 +2,7 @@
 - doc polishing
 - more improvements for truncated PNG files, thanks juyunsang 
 - improve corrupted jpg handling, thanks juyunsang
+- fix small test suite issues on os x
 
 23/4/17 started 8.5.4
 - don't depend on image width when setting n_lines, thanks kleisauke

test/test_foreign.py

@@ -169,7 +169,7 @@ class TestForeign(unittest.TestCase):
         self.file_loader("jpegload", self.jpeg_file, jpeg_valid)
         self.buffer_loader("jpegload_buffer", self.jpeg_file, jpeg_valid)
         self.save_load_buffer("jpegsave_buffer", "jpegload_buffer", self.colour,
-                             60)
+                             80)
         self.save_load("%s.jpg", self.mono)
         self.save_load("%s.jpg", self.colour)
 
@@ -264,9 +264,9 @@ class TestForeign(unittest.TestCase):
         self.save_load_file("test-5.tif", "[tile]", self.colour, 0)
         self.save_load_file("test-6.tif", "[tile,pyramid]", self.colour, 0)
         self.save_load_file("test-7.tif", 
-                            "[tile,pyramid,compression=jpeg]", self.colour, 60)
+                            "[tile,pyramid,compression=jpeg]", self.colour, 80)
         self.save_load_file("test-8.tif", "[bigtiff]", self.colour, 0)
-        self.save_load_file("test-9.tif", "[compression=jpeg]", self.colour, 60)
+        self.save_load_file("test-9.tif", "[compression=jpeg]", self.colour, 80)
         self.save_load_file("test-10.tif", 
                             "[tile,tile-width=256]", self.colour, 10)
 

test/test_histogram.py

@@ -127,7 +127,7 @@ class TestHistogram(unittest.TestCase):
 
         ent = im.hist_find().hist_entropy()
 
-        self.assertAlmostEqual(ent, 4.367, places = 3)
+        self.assertAlmostEqual(ent, 4.37, places = 2)
 
     def test_stdif(self):
         im = Vips.Image.new_from_file("images/йцук.jpg")