a couple of inconsistencies

make pmatchregex regex_error_desc return type match cppregex.cpp and
posixregex.c

make the extern declaration for loadsyms[] in options.c match the
one in symbols.c.

sys/share/pmatchregex.c

@@ -41,7 +41,7 @@ regex_compile(const char *s, struct nhregex *re)
     return TRUE;
 }
 
-const char *
+char *
 regex_error_desc(struct nhregex *re UNUSED, char *errbuf)
 {
     return strcpy(errbuf, "pattern match compilation error");