libsparse: deal with build warning messages

- mostly unused parameters, added defs.h to hold __unused macro
- read_all prototype not included, added output_file.h to acquire

Change-Id: Ib7ee00614acab53a6bd6a64f7e26a8c13dbe6297
diff --git a/libsparse/sparse_read.c b/libsparse/sparse_read.c
index 704bcfa..873c87c 100644
--- a/libsparse/sparse_read.c
+++ b/libsparse/sparse_read.c
@@ -29,6 +29,8 @@
 
 #include <sparse/sparse.h>
 
+#include "defs.h"
+#include "output_file.h"
 #include "sparse_crc32.h"
 #include "sparse_file.h"
 #include "sparse_format.h"
@@ -175,7 +177,8 @@
 }
 
 static int process_skip_chunk(struct sparse_file *s, unsigned int chunk_size,
-		int fd, unsigned int blocks, unsigned int block, uint32_t *crc32)
+		int fd __unused, unsigned int blocks,
+		unsigned int block __unused, uint32_t *crc32)
 {
 	int ret;
 	int chunk;