libiscsi fails to build with base-gcc because it uses -W arguments unknown
to gcc4. I think switching to ports-gcc is the simplest fix here.
Additionally this likes to pick up gnutls or libgcrypt during configure
so make sure it does not do that. The code ships with a local version for
md5 so there is nothing lost here.

-- 
:wq Claudio

Index: Makefile
===================================================================
RCS file: /cvs/ports/devel/libiscsi/Makefile,v
diff -u -p -r1.9 Makefile
--- Makefile	20 Jul 2025 14:53:29 -0000	1.9
+++ Makefile	17 Nov 2025 16:13:49 -0000
@@ -15,6 +15,10 @@ MAINTAINER=	Brad Smith <brad@comstyle.co
 # LGPLv2.1+, GPLv2+ and PD
 PERMIT_PACKAGE=	Yes
 
+# uses -Wvla -Wno-stringop-truncation
+COMPILER=	base-clang ports-gcc
+COMPILER_LANGS=	c
+
 WANTLIB=	c
 
 AUTOCONF_VERSION=	2.71
@@ -23,6 +27,8 @@ AUTOMAKE_VERSION=	1.16
 USE_GMAKE=	Yes
 CONFIGURE_STYLE= 	autoreconf
 
-CONFIGURE_ARGS+=	--disable-werror
+CONFIGURE_ARGS+=	--disable-werror \
+			--without-gnutls \
+			--without-libgcrypt
 
 .include <bsd.port.mk>