Allow install(1)'s create_tempfile() to work on Linux hosts

GLibc expects six 'X' characters in the mkstemp template argument and
will return EINVAL otherwise.

Reviewed By:	emaste, imp, mjg
Differential Revision: https://reviews.freebsd.org/D25662

usr.bin/xinstall/install.1

@@ -301,8 +301,8 @@ This is mainly for use in debugging the
 .Fx
 Ports Collection.
 .Sh FILES
-.Bl -tag -width "INS@XXXX" -compact
+.Bl -tag -width "INS@XXXXXX" -compact
-.It Pa INS@XXXX
+.It Pa INS@XXXXXX
 If either
 .Fl S
 option is specified, or the
@@ -312,9 +312,9 @@ or
 option is used in conjunction with the
 .Fl s
 option, temporary files named
-.Pa INS@XXXX ,
+.Pa INS@XXXXXX ,
 where
-.Pa XXXX
+.Pa XXXXXX
 is decided by
 .Xr mkstemp 3 ,
 are created in the target directory.

usr.bin/xinstall/xinstall.c

@@ -1161,7 +1161,7 @@ create_tempfile(const char *path, char *temp, size_t tsize)
 		p++;
 	else
 		p = temp;
-	(void)strncpy(p, "INS@XXXX", &temp[tsize - 1] - p);
+	(void)strncpy(p, "INS@XXXXXX", &temp[tsize - 1] - p);
 	temp[tsize - 1] = '\0';
 	return (mkstemp(temp));
 }