Running link-parser on amd64, there was an undefined reference to call_once.
This symbol comes from devel/libstdthreads.

Remove BROKEN-sparc64 as the symbols listed there are also found in
libstdthreads.

Index: Makefile
===================================================================
RCS file: /cvs/ports/textproc/link-grammar/Makefile,v
diff -u -p -r1.80 Makefile
--- Makefile	30 Aug 2025 09:34:00 -0000	1.80
+++ Makefile	15 Oct 2025 12:39:45 -0000
@@ -1,5 +1,3 @@
-BROKEN-sparc64 = Undefined references in liblink-grammar.so to mtx_lock, tss_set, and others
-
 ONLY_FOR_ARCHS-java =	i386 amd64
 ONLY_FOR_ARCHS =	${CLANG_ARCHS} ${LLVM_ARCHS}
 
@@ -8,6 +6,7 @@ COMMENT-java =		Java bindings for link-g
 COMMENT-python =	Python bindings for link-grammar
 
 VERSION =		5.12.6
+REVISION =		0
 DISTNAME =		link-grammar-${VERSION}
 PKGNAME-main =		${DISTNAME}
 PKGNAME-java =		link-grammar-java-${VERSION}
--- /dev/null	Wed Oct 15 23:49:51 2025
+++ patches/patch-link-grammar_Makefile_am	Wed Oct 15 23:38:43 2025
@@ -0,0 +1,13 @@
+Index: link-grammar/Makefile.am
+--- link-grammar/Makefile.am.orig
++++ link-grammar/Makefile.am
+@@ -81,6 +81,9 @@ liblink_grammar_la_LIBADD  += ${PTHREAD_LIBS}
+ # It seems no mathematical function is used now. Keep it to be on the safe side.
+ liblink_grammar_la_LIBADD  += -lm
+ 
++# for call_once
++liblink_grammar_la_LIBADD  += -lstdthreads
++
+ if WITH_CXXREGEX
+ dict-common/regex-morph.lo: AM_CFLAGS = -x c++ $(CXXFLAGS) $(WARN_CXXFLAGS)
+ dict-common/regex-morph.lo: CFLAGS =