Rename MBEDTLS_X509_INFO to !MBEDTLS_X509_REMOVE_INFO

The introduction of positive options to control the presence
of pre-existing functionality breaks the build for users of
handwritten configurations.

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/include/mbedtls/x509.h b/include/mbedtls/x509.h
index 44f2ed0..3091de1 100644
--- a/include/mbedtls/x509.h
+++ b/include/mbedtls/x509.h
@@ -316,7 +316,7 @@
                      mbedtls_x509_buf *serial );
 int mbedtls_x509_get_ext( unsigned char **p, const unsigned char *end,
                   mbedtls_x509_buf *ext, int tag );
-#if defined(MBEDTLS_X509_INFO)
+#if !defined(MBEDTLS_X509_REMOVE_INFO)
 int mbedtls_x509_sig_alg_gets( char *buf, size_t size, const mbedtls_x509_buf *sig_oid,
                        mbedtls_pk_type_t pk_alg, mbedtls_md_type_t md_alg,
                        const void *sig_opts );