Fix a warning on OpenSolaris

Add a missing #include statement to avoid a warning:
/src/qemu/net/tap-solaris.c: In function 'tap_open':
/src/qemu/net/tap-solaris.c:189: warning: implicit declaration of function 'error_report'

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

net/tap-solaris.c

@@ -38,6 +38,7 @@
 #include <net/if.h>
 #include <syslog.h>
 #include <stropts.h>
+#include "qemu-error.h"
 
 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 {