lib: af/hw: constify name fields

These strings are static data set in sub-modules and never modified.

lib/af.c

@@ -320,7 +320,7 @@ int aftrans_opt(const char *arg)
 /* type: 0=all, 1=getroute */
 void print_aflist(int type) {
     int count = 0;
-    char * txt;
+    const char * txt;
     struct aftype **afp;
 
     if (!sVafinit)

lib/hw.c

@@ -274,7 +274,7 @@ struct hwtype *get_hwntype(int type)
 /* type: 0=all, 1=ARPable */
 void print_hwlist(int type) {
     int count = 0;
-    char * txt;
+    const char * txt;
     struct hwtype **hwp;
 
     if (!sVhwinit)

lib/net-support.h

@@ -34,8 +34,8 @@
 
 /* This structure defines protocol families and their handlers. */
 struct aftype {
-    char *name;
-    char *title;
+    const char *name;
+    const char *title;
     int af;
     int alen;
     const char *(*print) (const char *);
@@ -49,15 +49,15 @@ struct aftype {
     int (*getmask) (char *src, struct sockaddr *mask, char *name);
 
     int fd;
-    char *flag_file;
+    const char *flag_file;
 };
 
 extern struct aftype *aftypes[];
 
 /* This structure defines hardware protocols and their handlers. */
 struct hwtype {
-    char *name;
-    char *title;
+    const char *name;
+    const char *title;
     int type;
     int alen;
     const char *(*print) (const char *);