mixer: Move floatmix to the audio mixer plugin

Move floatmix to the audiomixer plugin and change the name to
AUDIO_MIXER_DSP.
Add runtime selectable sse and sse2 optimizations.
Load the port mixer plugin dynamically based on the factory_name.
Add some more debug

spa/plugins/audiomixer/meson.build

@@ -1,7 +1,46 @@
-audiomixer_sources = ['audiomixer.c', 'mix-ops.c', 'plugin.c']
+audiomixer_sources = [
+	'audiomixer.c',
+	'mix-ops.c',
+	'mixer-dsp.c',
+	'plugin.c']
+
+simd_cargs = []
+simd_dependencies = []
+
+audiomixer_c = static_library('audiomixer_c',
+	['mix-ops-c.c' ],
+	c_args : ['-O3'],
+	include_directories : [spa_inc],
+	install : false
+)
+simd_dependencies += audiomixer_c
+
+if have_sse
+	audiomixer_sse = static_library('audiomixer_sse',
+		['mix-ops-sse.c' ],
+		c_args : [sse_args, '-O3', '-DHAVE_SSE'],
+		include_directories : [spa_inc],
+		install : false
+	)
+	simd_cargs += ['-DHAVE_SSE']
+	simd_dependencies += audiomixer_sse
+endif
+if have_sse2
+	audiomixer_sse2 = static_library('audiomixer_sse2',
+		['mix-ops-sse2.c' ],
+		c_args : [sse2_args, '-O3', '-DHAVE_SSE2'],
+		include_directories : [spa_inc],
+		install : false
+	)
+	simd_cargs += ['-DHAVE_SSE2']
+	simd_dependencies += audiomixer_sse2
+endif
 
 audiomixerlib = shared_library('spa-audiomixer',
                           audiomixer_sources,
+			  c_args : simd_cargs,
+			  link_with : simd_dependencies,
                           include_directories : [spa_inc],
+                          dependencies : [ mathlib ],
                           install : true,
                           install_dir : '@0@/spa/audiomixer/'.format(get_option('libdir')))