compress: upgraded to AudioCompress 2.0

Copied sources from
http://beesbuzz.biz/code/audiocompress/AudioCompress-2.0.tar.gz

[mk: created this patch under fluffy's name and fixed some gcc
signed/unsigned comparison warnings]

src/AudioCompress/compress.h

@@ -0,0 +1,40 @@
+/*! compress.h
+ *  interface to audio compression
+ *
+ *  (c)2007 busybee (http://beesbuzz.biz/)
+ *  Licensed under the terms of the LGPL. See the file COPYING for details.
+ */
+
+#ifndef COMPRESS_H
+#define COMPRESS_H
+
+#include <sys/types.h>
+
+//! Configuration values for the compressor object
+struct CompressorConfig {
+	int target;
+	int maxgain;
+	int smooth;
+};
+
+struct Compressor;
+
+//! Create a new compressor (use history value of 0 for default)
+struct Compressor *Compressor_new(unsigned int history);
+
+//! Delete a compressor
+void Compressor_delete(struct Compressor *);
+
+//! Set the history length
+void Compressor_setHistory(struct Compressor *, unsigned int history);
+
+//! Get the configuration for a compressor
+struct CompressorConfig *Compressor_getConfig(struct Compressor *);
+
+//! Process 16-bit signed data
+void Compressor_Process_int16(struct Compressor *, int16_t *data, unsigned int count);
+
+//! TODO: Compressor_Process_int32, Compressor_Process_float, others as needed
+
+//! TODO: functions for getting at the peak/gain/clip history buffers (for monitoring)
+#endif