Add text/x509aux to gitignore

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
diff --git a/.gitignore b/.gitignore
index 6ad374d..2f99952 100644
--- a/.gitignore
+++ b/.gitignore
@@ -80,6 +80,7 @@
 /test/fips_rngvs
 /test/fips_test_suite
 /test/ssltest_old
+/test/x509aux
 *.so*
 *.dylib*
 *.dll*