Add text/x509aux to gitignore

Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>

.gitignore

@@ -80,6 +80,7 @@ Makefile
 /test/fips_rngvs
 /test/fips_test_suite
 /test/ssltest_old
+/test/x509aux
 *.so*
 *.dylib*
 *.dll*