libsepol/tests: fix use of unitialized variable

When write_binary_policy() fails to open the binary policy, it calls
sepol_handle_destroy(f.handle) but structure f has not been initialized
at this point. Use variable handle instead.

This issue has been found using clang's static analyzer.

Signed-off-by: Nicolas Iooss <[email protected]>
diff --git a/libsepol/tests/test-downgrade.c b/libsepol/tests/test-downgrade.c
index 50807c1..963f3fa 100644
--- a/libsepol/tests/test-downgrade.c
+++ b/libsepol/tests/test-downgrade.c
@@ -254,7 +254,7 @@
 	if ((out_fp = fopen(path, "w" )) == NULL) {
 		fprintf(stderr, "Unable to open %s: %s\n", path,
 			strerror(errno));
-		sepol_handle_destroy(f.handle);
+		sepol_handle_destroy(handle);
 		return -1;
 	}