After the option was removed in R37:a46bc0f05f8b2ee10878ea1a1e88e312c93b3ca8, Krita would segfault at startup for me. This patch fixes that and removes other references to PACKAGERS_BUILD.
(In a response to a bug report, Boud had said that the option was also removed in the 3.1 branch. However, the option is still there at the moment. Is there anything I should do about 3.1?)