top(1): modernize a bit; reduce warnings

- Replace caddr_t with "void *". This reduces
the number of warnings at WARNS=6
- use "static" where possible
- sprinkle const where possible

This leaves at WARNS=6:
35 warnings in top.c
88 warnings in machine.c
7 warnings in commands.c

all of which are either "incompatible-pointer-types-discards-qualifiers"
or "cast-qual"

usr.bin/top/display.c

@@ -588,13 +588,10 @@ for (cpu = 0; cpu < num_cpus; cpu++) {
  *                for i_memory ONLY: cursor is on the previous line
  */
 
-char memory_buffer[MAX_COLS];
+static char memory_buffer[MAX_COLS];
 
 void
-i_memory(stats)
-
-int *stats;
-
+i_memory(int *stats)
 {
     fputs("\nMem: ", stdout);
     lastline++;
@@ -605,10 +602,7 @@ int *stats;
 }
 
 void
-u_memory(stats)
-
-int *stats;
-
+u_memory(int *stats)
 {
     static char new[MAX_COLS];
 

usr.bin/top/machine.c

@@ -53,7 +53,6 @@
 #define	SMPUNAMELEN	13
 #define	UPUNAMELEN	15
 
-extern struct process_select ps;
 extern struct timeval timeout;
 static int smpmode;
 enum displaymodes displaymode;
@@ -743,7 +742,7 @@ get_io_total(struct kinfo_proc *pp)
 
 static struct handle handle;
 
-caddr_t
+void *
 get_process_info(struct system_info *si, struct process_select *sel,
     int (*compare)(const void *, const void *))
 {

usr.bin/top/machine.h

@@ -84,8 +84,9 @@ int	 proc_owner(int pid);
 
 /* non-int routines typically used by the machine dependent module */
 char	*printable(char *string);
+extern struct process_select ps;
 
-caddr_t
+void *
 get_process_info(struct system_info *si, struct process_select *sel,
     int (*compare)(const void *, const void *));
 

usr.bin/top/screen.c

@@ -39,18 +39,18 @@ char ch_erase;
 char ch_kill;
 char smart_terminal;
 char PC;
-char termcap_buf[1024];
-char string_buffer[1024];
-char home[15];
-char lower_left[15];
+static char termcap_buf[1024];
+static char string_buffer[1024];
+static char home[15];
+static char lower_left[15];
 char *clear_line;
-char *clear_screen;
+static char *clear_screen;
 char *clear_to_end;
 char *cursor_motion;
-char *start_standout;
-char *end_standout;
-char *terminal_init;
-char *terminal_end;
+static char *start_standout;
+static char *end_standout;
+static char *terminal_init;
+static char *terminal_end;
 
 static struct termios old_settings;
 static struct termios new_settings;

usr.bin/top/top.c

@@ -40,7 +40,7 @@
 /* Size of the stdio buffer given to stdout */
 #define Buffersize	2048
 
-char *copyright =
+char copyright[] =
     "Copyright (c) 1984 through 1996, William LeFebvre";
 
 typedef void sigret_t;
@@ -211,7 +211,7 @@ char *argv[];
 
     struct system_info system_info;
     struct statics statics;
-    caddr_t processes;
+    void * processes;
 
     static char tempbuf1[50];
     static char tempbuf2[50];

usr.bin/top/top.h

@@ -53,7 +53,7 @@ extern int (*compares[])(const void*, const void*);
 char* kill_procs(char *);
 char* renice_procs(char *);
 
-extern char *copyright;
+extern char copyright[];
 /* internal routines */
 void quit(int);
 

usr.bin/top/username.c

@@ -56,7 +56,7 @@ struct hash_el {
 
 /* K&R requires that statically declared tables be initialized to zero. */
 /* We depend on that for hash_table and YOUR compiler had BETTER do it! */
-struct hash_el hash_table[Table_size];
+static struct hash_el hash_table[Table_size];
 
 
 char *username(uid)