tests/Makefile: Add PCM function

For use with the "pcm" command.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

tests/Makefile

@@ -108,6 +108,10 @@ FRAMECRC = $(call ALLYES, $(1)_DEMUXER $(2:%=%_DECODER) $(3)                  \
                           PCM_S16LE_ENCODER RAWVIDEO_ENCODER FRAMECRC_MUXER   \
                           PIPE_PROTOCOL FILE_PROTOCOL)
 
+# Variant of DEMDEC for use with the "pcm" command.
+PCM = $(call ALLYES, $(1)_DEMUXER $(2)_DECODER  $(3) FILE_PROTOCOL            \
+                     PCM_S16LE_ENCODER PCM_S16LE_MUXER PIPE_PROTOCOL)
+
 DEMMUX  = $(call ALLYES, $(1)_DEMUXER $(2)_MUXER $(3) FILE_PROTOCOL)
 
 # Variant of FRAMECRC for the cases with -lavfi where no demuxer is involved.