Compile on Freebsd (#1044)

* Compile on Freebsd

Small changes needed for compilation on Freebsd. Note that you'll have
to pass -DEQEMU_BUILD_ZLIB=OFF on the cmake command line. The bundled
zlib-ng does not build on Freebsd even though mainline zlib-ng does.

* Fix build errors: typo

common/proc_launcher.h

@@ -24,6 +24,10 @@
 #include <vector>
 #include <map>
 
+#ifdef __FreeBSD__
+#include <unistd.h>
+#endif
+
 //I forced this object to become a singleton because it registers its
 //signal handler for UNIX
 class ProcLauncher {