meson: Added meson.build for audiomixmatrix and timecode

https://bugzilla.gnome.org/show_bug.cgi?id=779154
diff --git a/gst/audiomixmatrix/meson.build b/gst/audiomixmatrix/meson.build
new file mode 100644
index 0000000..4a6bc57
--- /dev/null
+++ b/gst/audiomixmatrix/meson.build
@@ -0,0 +1,12 @@
+audiomixmatrix_sources = [
+  'gstaudiomixmatrix.c',
+]
+
+gstaudiomixmatrix = library('gstaudiomixmatrix',
+  audiomixmatrix_sources,
+  c_args : gst_plugins_bad_args,
+  include_directories : [configinc],
+  dependencies : [gstbase_dep, gstaudio_dep],
+  install : true,
+  install_dir : plugins_install_dir,
+)
diff --git a/gst/meson.build b/gst/meson.build
index 17aa3d3..86c59b4 100644
--- a/gst/meson.build
+++ b/gst/meson.build
@@ -6,6 +6,7 @@
 subdir('audiobuffersplit')
 subdir('audiofxbad')
 subdir('audiomixer')
+subdir('audiomixmatrix')
 subdir('audiovisualizers')
 subdir('autoconvert')
 subdir('bayer')
@@ -49,6 +50,7 @@
 subdir('speed')
 subdir('stereo')
 subdir('subenc')
+subdir('timecode')
 subdir('videofilters')
 subdir('videoframe_audiolevel')
 subdir('videoparsers')
diff --git a/gst/timecode/meson.build b/gst/timecode/meson.build
new file mode 100644
index 0000000..ac74e12
--- /dev/null
+++ b/gst/timecode/meson.build
@@ -0,0 +1,14 @@
+timecode_sources = [
+  'plugin.c',
+  'gsttimecodestamper.c',
+  'gstavwait.c'
+]
+
+gsttimecode = library('gsttimecode',
+  timecode_sources,
+  c_args : gst_plugins_bad_args,
+  include_directories : [configinc],
+  dependencies : [gstbase_dep, gstaudio_dep, gstvideo_dep],
+  install : true,
+  install_dir : plugins_install_dir,
+)