fix failure to free memory

The applypatch function is somewhat sloppy about freeing memory (since
it was originally a standalone binary).  Fix some of that.

Change-Id: Ifd44d71ea189c0b5115493119fd57bc37533fd59
diff --git a/applypatch/applypatch.h b/applypatch/applypatch.h
index a78c89b..e8ac3cc 100644
--- a/applypatch/applypatch.h
+++ b/applypatch/applypatch.h
@@ -62,7 +62,7 @@
 
 int LoadFileContents(const char* filename, FileContents* file,
                      int retouch_flag);
-int SaveFileContents(const char* filename, FileContents file);
+int SaveFileContents(const char* filename, const FileContents* file);
 void FreeFileContents(FileContents* file);
 int FindMatchingPatch(uint8_t* sha1, char** const patch_sha1_str,
                       int num_patches);