Let dbm's datum::dptr use the right type.

According to POSIX, it should use void *, not char *. Unfortunately, the
dsize field also has the wrong type. It should be size_t. I'm not going
to change that, as that will break the ABI.

Reviewed by:	pfg
Differential Revision:	https://reviews.freebsd.org/D6647

include/ndbm.h

@@ -52,7 +52,7 @@
 #define	DBM_SUFFIX	".db"
 
 typedef struct {
-	char *dptr;
+	void *dptr;
 	int dsize;
 } datum;
 

lib/libc/db/man/dbm.3

@@ -15,7 +15,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 19, 2015
+.Dd May 30, 2016
 .Dt DBM 3
 .Os
 .Sh NAME
@@ -66,7 +66,7 @@ is declared in
 .In ndbm.h :
 .Bd -literal
 typedef struct {
-	char *dptr;
+	void *dptr;
 	int dsize;
 } datum;
 .Ed