minijail: Add a way to specify the path of libminijailpreload.so

This change will allow tests that use the minijail0 binary. In
particular, this is interesting because it's the only way that the
libminijailpreload.so can be used.

Bug: None
Test: make tests

Change-Id: I681b7cda65910c339f4a91a0af01ba7cec2c3742
diff --git a/minijail0_cli.h b/minijail0_cli.h
index d4eb440..583c763 100644
--- a/minijail0_cli.h
+++ b/minijail0_cli.h
@@ -16,8 +16,9 @@
 
 struct minijail;
 
-int parse_args(struct minijail *j, int argc, char * const argv[],
-	       int *exit_immediately, ElfType *elftype);
+int parse_args(struct minijail *j, int argc, char *const argv[],
+	       int *exit_immediately, ElfType *elftype,
+	       const char **preload_path);
 
 #ifdef __cplusplus
 }; /* extern "C" */