Make function mbedtls_ssl_set_hostname(...) as optional

Now function mbedtls_ssl_set_hostname is compile-time configurable
in config.h with define MBEDTLS_X509_REMOVE_HOSTNAME_VERIFICATION.
This affects to many x509 API's. See config.h for details.
diff --git a/scripts/config.pl b/scripts/config.pl
index e4648de..77358b3 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -41,6 +41,7 @@
 #   MBEDTLS_X509_REMOVE_INFO
 #   MBEDTLS_X509_CRT_REMOVE_TIME
 #   MBEDTLS_X509_CRT_REMOVE_SUBJECT_ISSUER_ID
+#   MBEDTLS_X509_REMOVE_HOSTNAME_VERIFICATION
 #   MBEDTLS_ZLIB_SUPPORT
 #   MBEDTLS_PKCS11_C
 #   and any symbol beginning _ALT
@@ -106,6 +107,7 @@
 MBEDTLS_X509_REMOVE_INFO
 MBEDTLS_X509_CRT_REMOVE_TIME
 MBEDTLS_X509_CRT_REMOVE_SUBJECT_ISSUER_ID
+MBEDTLS_X509_REMOVE_HOSTNAME_VERIFICATION
 MBEDTLS_ZLIB_SUPPORT
 MBEDTLS_PKCS11_C
 MBEDTLS_NO_UDBL_DIVISION