pcm_resample: don't resample partial samples

Added assertions which ensure that there are no partial samples in the
source buffer.

src/pcm_resample_libsamplerate.c

@@ -22,6 +22,7 @@
 #include "log.h"
 #include "utils.h"
 
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -75,6 +76,9 @@ pcm_resample_16(uint8_t channels,
 	size_t data_out_size;
 	int error;
 
+	assert((src_size % (sizeof(*src_buffer) * channels)) == 0);
+	assert((dest_size % (sizeof(*dest_buffer) * channels)) == 0);
+
 	if (convalgo < 0)
 		convalgo = pcm_resample_get_converter();