CLEANUP: compression: remove unused reset functions

It's unclear what purpose these functions used to server, however they
are not used anywhere, one good reason to remove them.
diff --git a/include/types/compression.h b/include/types/compression.h
index 376eea9..d062d23 100644
--- a/include/types/compression.h
+++ b/include/types/compression.h
@@ -64,7 +64,6 @@
 	int (*add_data)(struct comp_ctx *comp_ctx, const char *in_data, int in_len, struct buffer *out);
 	int (*flush)(struct comp_ctx *comp_ctx, struct buffer *out);
 	int (*finish)(struct comp_ctx *comp_ctx, struct buffer *out);
-	int (*reset)(struct comp_ctx *comp_ctx);
 	int (*end)(struct comp_ctx **comp_ctx);
 	struct comp_algo *next;
 };
diff --git a/src/compression.c b/src/compression.c
index fd053d5..004c5e2 100644
--- a/src/compression.c
+++ b/src/compression.c
@@ -59,28 +59,28 @@
 static int identity_add_data(struct comp_ctx *comp_ctx, const char *in_data, int in_len, struct buffer *out);
 static int identity_flush(struct comp_ctx *comp_ctx, struct buffer *out);
 static int identity_finish(struct comp_ctx *comp_ctx, struct buffer *out);
-static int identity_reset(struct comp_ctx *comp_ctx);
 static int identity_end(struct comp_ctx **comp_ctx);
 
 #ifdef USE_ZLIB
+
 static int gzip_init(struct comp_ctx **comp_ctx, int level);
 static int raw_def_init(struct comp_ctx **comp_ctx, int level);
 static int deflate_init(struct comp_ctx **comp_ctx, int level);
 static int deflate_add_data(struct comp_ctx *comp_ctx, const char *in_data, int in_len, struct buffer *out);
 static int deflate_flush(struct comp_ctx *comp_ctx, struct buffer *out);
 static int deflate_finish(struct comp_ctx *comp_ctx, struct buffer *out);
-static int deflate_reset(struct comp_ctx *comp_ctx);
 static int deflate_end(struct comp_ctx **comp_ctx);
+
 #endif /* USE_ZLIB */
 
 
 const struct comp_algo comp_algos[] =
 {
-	{ "identity",     8, "identity", 8, identity_init, identity_add_data, identity_flush, identity_finish, identity_reset, identity_end },
+	{ "identity",     8, "identity", 8, identity_init, identity_add_data, identity_flush, identity_finish, identity_end },
 #ifdef USE_ZLIB
-	{ "deflate",      7, "deflate",  7, deflate_init,  deflate_add_data,  deflate_flush,  deflate_finish,  deflate_reset,  deflate_end },
-	{ "raw-deflate", 11, "deflate",  7, raw_def_init,  deflate_add_data,  deflate_flush,  deflate_finish,  deflate_reset,  deflate_end },
-	{ "gzip",         4, "gzip",     4, gzip_init,     deflate_add_data,  deflate_flush,  deflate_finish,  deflate_reset,  deflate_end },
+	{ "deflate",      7, "deflate",  7, deflate_init,  deflate_add_data,  deflate_flush,  deflate_finish,  deflate_end },
+	{ "raw-deflate", 11, "deflate",  7, raw_def_init,  deflate_add_data,  deflate_flush,  deflate_finish,  deflate_end },
+	{ "gzip",         4, "gzip",     4, gzip_init,     deflate_add_data,  deflate_flush,  deflate_finish,  deflate_end },
 #endif /* USE_ZLIB */
 	{ NULL,       0, NULL,          0, NULL ,         NULL,              NULL,           NULL,           NULL }
 };
@@ -665,15 +665,6 @@
 	return deflate_flush_or_finish(comp_ctx, out, Z_FINISH);
 }
 
-static int deflate_reset(struct comp_ctx *comp_ctx)
-{
-	z_stream *strm = &comp_ctx->strm;
-
-	if (deflateReset(strm) == Z_OK)
-		return 0;
-	return -1;
-}
-
 static int deflate_end(struct comp_ctx **comp_ctx)
 {
 	z_stream *strm = &(*comp_ctx)->strm;