NetBSD: Build on NetBSD

Minor patch against so building on NetBSD is possible.

src/arch/sparc/remote_gdb.cc

@@ -116,6 +116,7 @@
  * "Stub" to allow remote cpu to debug over a serial line using gdb.
  */
 
+#include <signal.h>
 #include <sys/signal.h>
 #include <unistd.h>
 

src/base/remote_gdb.cc

@@ -116,6 +116,7 @@
  * "Stub" to allow remote cpu to debug over a serial line using gdb.
  */
 
+#include <signal.h>
 #include <sys/signal.h>
 #include <unistd.h>
 

src/sim/syscall_emul.hh

@@ -33,7 +33,8 @@
 #define __SIM_SYSCALL_EMUL_HH__
 
 #define NO_STAT64 (defined(__APPLE__) || defined(__OpenBSD__) || \
-                   defined(__FreeBSD__) || defined(__CYGWIN__))
+  defined(__FreeBSD__) || defined(__CYGWIN__) || \
+  defined(__NetBSD__))
 
 ///
 /// @file syscall_emul.hh