Revert "mixxx: update to git HEAD"

Looks like unfinished development

This reverts commit ee4d6d56d6.

recipes-misc/recipes-multimedia/mixxx/files/0004-add-vamp-float-math-build-option-to-force-vamp-calcu.patch

@@ -74,12 +74,14 @@ diff --git a/SConstruct b/SConstruct
 index 301fd3d..7fc552a 100644
 --- a/SConstruct
 +++ b/SConstruct
-@@ -65,7 +65,8 @@ available_features = [features.Mad,
+@@ -63,8 +63,9 @@ available_features = [features.Mad,
+                       features.IPod,
+                       features.FFMPEG,
  
-                       # Experimental features
-                       features.OpenGLES,
--                      features.QtKeychain
-+                      features.QtKeychain,
+-		     # Experimental features
+-		     features.OpenGLES
++                      # Experimental features
++                      features.OpenGLES,
 +                      features.VampFloat
                        ]
  

recipes-misc/recipes-multimedia/mixxx/mixxx_git.bb

@@ -42,7 +42,7 @@ SRC_URI = " \
     file://0004-add-vamp-float-math-build-option-to-force-vamp-calcu.patch \
     file://0005-Fix-release-build-with-Qt-5.10.patch \
 "
-SRCREV = "24028f2e8a28210fe45d8b67f2bb44d580587261"
+SRCREV = "b6d29e53d3ae74cd040a5d5ecbe742f9c385575a"
 S = "${WORKDIR}/git"
 PV = "2.0.0+git${SRCPV}"