security/gnutls: fix build with lld 17

Since lld17 the default is to have the LDFLAGS --no-undefined-version
activated by default, which means that versions scripts should not
contain undefined symbols

2 bugs in gnutls:
1/ the configure scripts tests an empty binary against a list of version
symbols, meaning it breaks in configure (hence the activation of
--enable-ld-version-scripts) which means currently provided gnutls
packages are build without version scripts which breaks existing
installations...
2/ the version script used to link the binary can contain undefined
symbols depending on the options used to build (hence the addition of
the LDFLAGS.

security/gnutls/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	gnutls
 PORTVERSION=	3.7.10
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	security net
 MASTER_SITES=	GNUPG/gnutls/v${PORTVERSION:R}
 
@@ -31,7 +31,9 @@ CONFIGURE_ARGS=	--disable-guile \
 		--without-brotli \
 		--without-zstd \
 		--without-tpm \
-		--without-tpm2
+		--without-tpm2 \
+		--enable-ld-version-script
+LDFLAGS=	-Wl,--undefined-version
 MAKE_ENV=	MAKEINFOFLAGS=--no-split
 INSTALL_TARGET=	install-strip
 TEST_TARGET=	check