I am uploading a NMU that fixes this.
Please find the debdiff attached that builds on the experimental version.
diff -Nru xjdic-24/debian/changelog xjdic-24/debian/changelog
--- xjdic-24/debian/changelog 2023-10-02 10:05:01.000000000 +0000
+++ xjdic-24/debian/changelog 2024-05-07 16:30:08.000000000 +0000
@@ -1,3 +1,10 @@
+xjdic (24-11.2) unstable; urgency=medium
+
+ * Non-maintainer upload.
+ * Fix missing function declarations. Closes: #1066228
+
+ -- Bastian Germann <b...@debian.org> Tue, 07 May 2024 16:30:08 +0000
+
xjdic (24-11.1) experimental; urgency=medium
* Non-maintainer upload.
diff -Nru xjdic-24/debian/patches/missing-function-declarations.patch
xjdic-24/debian/patches/missing-function-declarations.patch
--- xjdic-24/debian/patches/missing-function-declarations.patch 1970-01-01
00:00:00.000000000 +0000
+++ xjdic-24/debian/patches/missing-function-declarations.patch 2024-05-07
16:28:31.000000000 +0000
@@ -0,0 +1,70 @@
+diff -u xjdic-24/exjdxgen.c xjdic-24/exjdxgen.c
+--- xjdic-24/exjdxgen.c
++++ xjdic-24/exjdxgen.c
+@@ -22,7 +22,7 @@
+ #include <sys/stat.h>
+
+ #include <stdio.h>
+-/*#include <stdlib.h>*/
++#include <stdlib.h>
+ #include <ctype.h>
+ #include <string.h>
+ #include "xjdic.h"
+diff -u xjdic-24/xjdclient.c xjdic-24/xjdclient.c
+--- xjdic-24/xjdclient.c
++++ xjdic-24/xjdclient.c
+@@ -32,6 +32,7 @@
+ #include <sys/socket.h>
+ #include <netinet/in.h>
+ #include <netdb.h>
++#include <arpa/inet.h>
+ #include <sys/stat.h>
+ #include <sys/time.h>
+ #include <stdlib.h>
+diff -u xjdic-24/xjdfrontend.c xjdic-24/xjdfrontend.c
+--- xjdic-24/xjdfrontend.c
++++ xjdic-24/xjdfrontend.c
+@@ -196,7 +196,6 @@
+ void RadSet();
+ void Verbtoggle();
+ void FiltSet();
+-void xjdicrc();
+ void DoRADICALS();
+ int Vlookup();
+ void AppKanji(unsigned char c1,unsigned char c2);
+diff -u xjdic-24/xjdic.h xjdic-24/xjdic.h
+--- xjdic-24/xjdic.h
++++ xjdic-24/xjdic.h
+@@ -71,3 +71,7 @@
+ long xjdrsp_dicloc;
+ unsigned char xjdrsp_resstr[512];
+ } RSP_PDU;
++
++void EMtoggle();
++void xjdicrc();
++unsigned char dbchar(unsigned long xit);
+diff -u xjdic-24/xjdsa.c xjdic-24/xjdsa.c
+--- xjdic-24/xjdsa.c
++++ xjdic-24/xjdsa.c
+@@ -30,6 +30,8 @@
+ #include <signal.h>
+ #include "xjdic.h"
+
++int Kstrcmp(int klen,unsigned char *str1);
++unsigned long jindex(unsigned long xit);
+ unsigned char Dnamet[10][100],XJDXnamet[10][100];
+ unsigned char CBname[100];
+ unsigned char *dicbufft[10];
+diff -u xjdic-24/xjdserver.c xjdic-24/xjdserver.c
+--- xjdic-24/xjdserver.c
++++ xjdic-24/xjdserver.c
+@@ -36,7 +36,9 @@
+
+ void xjdicrc();
+ void DicSet ();
++int Kstrcmp(int klen,unsigned char *str1);
+ unsigned char *DicName(int dn);
++unsigned long jindex(unsigned long xit);
+
+ int portno=XJ_PORTNO;
+ int DontFork = FALSE;
diff -Nru xjdic-24/debian/patches/series xjdic-24/debian/patches/series
--- xjdic-24/debian/patches/series 2023-10-02 10:05:01.000000000 +0000
+++ xjdic-24/debian/patches/series 2024-05-07 16:29:32.000000000 +0000
@@ -1 +1,2 @@
debian.patch
+missing-function-declarations.patch
