Add a `bind' builtin command, which is simply a wrapper around libedit's

builtin command of the same name. This allows the key bindings for the
shell's line editor to be changed.

MFC after:	2 weeks

bin/sh/builtins.def

@@ -92,3 +92,4 @@ waitcmd		wait
 aliascmd	alias
 ulimitcmd	ulimit
 testcmd		test [
+bindcmd		bind

bin/sh/histedit.c

@@ -480,6 +480,16 @@ str_to_event(char *str, int last)
 	}
 	return (he.num);
 }
+
+int
+bindcmd(int argc, char **argv)
+{
+
+	if (el == NULL)
+		error("line editing is disabled");
+	return (el_parse(el, argc, argv));
+}
+
 #else
 #include "error.h"
 
@@ -491,4 +501,12 @@ histcmd(int argc, char **argv)
 	/*NOTREACHED*/
 	return (0);
 }
+
+int
+bindcmd(int argc, char **argv)
+{
+
+	error("not compiled with line editing support");
+	return (0);
+}
 #endif

bin/sh/myhistedit.h

@@ -45,4 +45,5 @@ void sethistsize(const char *);
 int histcmd(int, char **);
 int not_fcnumber(char *);
 int str_to_event(char *, int);
+int bindcmd(int, char **);
 

bin/sh/sh.1

@@ -1279,6 +1279,10 @@ Execute the specified builtin command,
 .Ar cmd .
 This is useful when the user wishes to override a shell function
 with the same name as a builtin command.
+.It Ic bind Oo Fl aeklrsv Oc Oo Ar key Oo Ar command Oc Oc
+List or alter key bindings for the line editor.
+This command is documented in
+.Xr editrc 5 .
 .It Ic cd Oo Fl LP Oc Op Ar directory
 Switch to the specified
 .Ar directory ,