mixxx: upgrade to latest maste to fix build with current oe

Something changed in scons/python3:
| TypeError: changed_since_last_build_node() takes 3 positional arguments but 4 were given:

Guess this one fixed it:

Author: Uwe Klotz <uklotz@mixxx.org>
Date:   Fri Aug 9 15:18:05 2019 +0200

    Fix signature of changed_since_last_build_node() for SCons 3.1.x

    Add a 4th parameter with default value:
    https://scons.org/doc/3.1.0/HTML/scons-api/SCons.Node-module.html#changed_since_last_build_nodehttps://scons.org/doc/3.1.0/HTML/scons-api/SCons.Node-module.html

Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>

recipes-musicians/mixxx/mixxx_git.bb

@@ -47,7 +47,7 @@ SRC_URI = " \
     file://0004-build-mixxx.py-Fix-build-with-recent-python3.patch \
     file://0005-Do-not-add-host-libdir-to-LDPATH-rpath.patch \
 "
-SRCREV = "6ae9e7947c743ab4cc3e54a6f09109d7558e7c50"
+SRCREV = "b679fd37093826efa7ab81b3d4679d9a88b02dbb"
 S = "${WORKDIR}/git"
 PV = "2.2.1+git${SRCPV}"