fix this mess of libraries

filter/delay.h

@@ -0,0 +1,13 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+typedef struct delay_line_t {
+	float *buffer;
+	uint32_t delay;
+	uint32_t idx;
+} delay_line_t;
+
+void init_delay_line(delay_line_t *dl, uint32_t delay_samples);
+float delay_line(delay_line_t *dl, float in);
+void exit_delay_line(delay_line_t *dl);