druntime: Add more static asserts

Author: yelninei

druntime/src/core/sys/posix/sys/un.d

@@ -113,3 +113,7 @@ else version (Hurd)
         byte[108]   sun_path;
     }
 }
+else
+{
+    static assert(false, "Unsupported platform");
+}

druntime/src/core/sys/posix/termios.d

@@ -928,6 +928,11 @@ else version (Hurd)
     enum TCOOFF     = 0;
     enum TCOON      = 1;
 }
+else
+{
+    static assert(false, "Unsupported platform");
+}
+
 
 /*
 speed_t cfgetispeed(const scope termios*);