BUILD: remove dependency to zlib.h

The build was dependent of the zlib.h header, regardless of the USE_ZLIB
option. The fix consists of several #ifdef in the source code.

It removes the overhead of the zstream structure in the session when you
don't use the option.

include/types/compression.h

@@ -23,8 +23,12 @@
 #ifndef _TYPES_COMP_H
 #define _TYPES_COMP_H
 
+#ifdef USE_ZLIB
+
 #include <zlib.h>
 
+#endif /* USE_ZLIB */
+
 struct comp {
 	struct comp_algo *algos;
 	struct comp_type *types;
@@ -32,7 +36,9 @@ struct comp {
 };
 
 struct comp_ctx {
+#ifdef USE_ZLIB
 	z_stream strm; /* zlib stream */
+#endif /* USE_ZLIB */
 };
 
 struct comp_algo {

include/types/session.h

@@ -33,6 +33,7 @@
 
 #include <types/channel.h>
 #include <types/compression.h>
+
 #include <types/proto_http.h>
 #include <types/proxy.h>
 #include <types/queue.h>

src/compression.c

@@ -13,6 +13,7 @@
 
 #include <stdio.h>
 
+#ifdef USE_ZLIB
 /* Note: the crappy zlib and openssl libs both define the "free_func" type.
  * That's a very clever idea to use such a generic name in general purpose
  * libraries, really... The zlib one is easier to redefine than openssl's,
@@ -21,6 +22,7 @@
 #define free_func zlib_free_func
 #include <zlib.h>
 #undef free_func
+#endif /* USE_ZLIB */
 
 #include <common/compat.h>
 
@@ -200,6 +202,8 @@ int http_compression_buffer_end(struct session *s, struct buffer **in, struct bu
 	int left;
 	struct http_msg *msg = &s->txn.rsp;
 	struct buffer *ib = *in, *ob = *out;
+
+#ifdef USE_ZLIB
 	int ret;
 
 	/* flush data here */
@@ -212,6 +216,8 @@ int http_compression_buffer_end(struct session *s, struct buffer **in, struct bu
 	if (ret < 0)
 		return -1; /* flush failed */
 
+#endif /* USE_ZLIB */
+
 	if (ob->i > 8) {
 		/* more than a chunk size => some data were emitted */
 		char *tail = ob->p + ob->i;