Add 'nibbles' to gdb.print_options

When I rebased and updated the print_options patch, I forgot to update
print_options to add the new 'nibbles' feature to the result.  This
patch fixes the oversight.  I'm checking this in.

gdb/python/py-prettyprint.c

@@ -753,6 +753,8 @@ gdbpy_print_options (PyObject *unused1, PyObject *unused2)
 		      opts.static_field_print) < 0
       || set_boolean (result.get (), "deref_refs",
 		      opts.deref_ref) < 0
+      || set_boolean (result.get (), "nibbles",
+		      opts.nibblesprint) < 0
       || set_boolean (result.get (), "summary",
 		      opts.summary) < 0
       || set_unsigned (result.get (), "max_elements",

gdb/testsuite/gdb.python/py-format-string.exp

@@ -1122,11 +1122,13 @@ proc test_print_options {} {
     gdb_test "python print('format' in gdb.print_options())" "False" \
 	"examine format"
 
-    check_format_string "a_point_t" "format='t'" \
-	"Pretty Point \\(101010, 1100\\)" \
+    check_format_string "a_point_t" "format='t', nibbles=True" \
+	"Pretty Point \\(0010.1010, 1100\\)" \
 	"print in binary to fetch options"
     gdb_test "python print(saved_options\['format'\] == 't')" "True" \
 	"format was set"
+    gdb_test "python print(saved_options\['nibbles'\])" "True" \
+	"nibbles was set"
 
     check_format_string "a_point_t" "summary=True" \
 	"No Data" \