dhcp: security bump to version 4.1-ESV-R4

Bump to version 4.1-ESV-R4 to fix CVE-2011-4539

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/dhcp/dhcp.mk

@@ -4,7 +4,7 @@
 #
 #############################################################
 
-DHCP_VERSION  = 4.1-ESV-R3
+DHCP_VERSION  = 4.1-ESV-R4
 DHCP_SITE     = http://ftp.isc.org/isc/dhcp
 DHCP_CONF_ENV = ac_cv_file__dev_random=yes
 DHCP_CONF_OPT = \