Fix build against musl

src/bin/perfdhcp/command_options.cc

@@ -22,6 +22,9 @@
 #include <unistd.h>
 #include <fstream>
 
+#ifdef HAVE_OPTRESET
+extern int optreset;
+#endif
 
 using namespace std;
 using namespace isc;

src/lib/dhcp/pkt_filter_lpf.cc

@@ -12,10 +12,10 @@
 #include <dhcp/protocol_util.h>
 #include <exceptions/exceptions.h>
 #include <fcntl.h>
+#include <net/ethernet.h>
 #include <linux/filter.h>
 #include <linux/if_ether.h>
 #include <linux/if_packet.h>
-#include <net/ethernet.h>
 
 namespace {