Add pthread.h include for os_Fuchsia
Fuchsia is a new operating system (https://fuchsia.googlesource.com/)
that supports pthreads for threading. CMake has support for Fuchsia:
so this wires up the #define.
@@ -274,7 +274,7 @@ typedef char* caddr_t;
#else /* !defined(Userspace_os_Windows) */
#include <sys/socket.h>
-#if defined(__Userspace_os_DragonFly) || defined(__Userspace_os_FreeBSD) || defined(__Userspace_os_Linux) || defined(__Userspace_os_NetBSD) || defined(__Userspace_os_OpenBSD) || defined(__Userspace_os_NaCl)
+#if defined(__Userspace_os_DragonFly) || defined(__Userspace_os_FreeBSD) || defined(__Userspace_os_Linux) || defined(__Userspace_os_NetBSD) || defined(__Userspace_os_OpenBSD) || defined(__Userspace_os_NaCl) || defined(__Userspace_os_Fuchsia)
#include <pthread.h>
#endif
typedef pthread_mutex_t userland_mutex_t;
