https://bugs.gentoo.org/870895
https://rt.cpan.org/Public/Bug/Display.html?id=145874

Add missing function prototypes.  This avoids implicit function
declarations when building Nilsimsa.xs and build failures with future
compilers.

--- a/nilsimsa.h
+++ b/nilsimsa.h
@@ -47,6 +47,8 @@ int nilsimsa(struct nsrecord *a,struct nsrecord *b);
 void aggregate(int n);
 void codetostr(struct nsrecord *a,char *str);
 int strtocode(char *str,struct nsrecord *a);
+void makecode(struct nsrecord *a);
+void clear(struct nsrecord *a);
 
 int accbuf(unsigned char *buf,int len,struct nsrecord *a);
 void dprint(char *msg);