Thanks for finding this out. After getting the latest version of gnustep base, this problem got solved.
Unfortunately, another one appeared:
checking for libgnutls-config... no
checking for libgnutls - version >= 1.4.0... no
*** The libgnutls-config script installed by libgnutls could not be found
*** If libtgnuls-config was installed in PREFIX, make sure PREFIX/bin is in
*** your path.
no
You do not appear to have usable libgnutls headers/library.
Building without them will disable SSL/TLS/HTTPS in NSStream,
NSFileHandle, NSURLHandle and NSURLConnection.
If you really want to build gnustep-base without TLS support,
add --disable-tls to the configure arguments.
configure: error: Missing support for TLS functionality.This problem is described in
bug #37709: gnutls deprecated gnutls-config, but I have recent packages of both gnutls and pkg-config installed: