os: make GenerateRandomData() independent of XCSECURITY

The function itself does not depend on the macro. Move it outside
of the ifdef guard and remove the identical copy in XWIN.

This is step 1 towards removing the duplication in winauth.c and moving
the OS specifics to os/

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Jon Turney <jon.turney@dronecode.org.uk>

hw/xwin/winauth.c

@@ -68,16 +68,6 @@ static xcb_auth_info_t auth_info;
  */
 
 #ifndef XCSECURITY
-void
-GenerateRandomData(int len, char *buf)
-{
-    int fd;
-
-    fd = open("/dev/urandom", O_RDONLY);
-    read(fd, buf, len);
-    close(fd);
-}
-
 static char cookie[16];         /* 128 bits */
 
 XID

os/auth.c

@@ -302,6 +302,8 @@ GenerateAuthorization(unsigned name_length,
     return -1;
 }
 
+#endif                          /* XCSECURITY */
+
 void
 GenerateRandomData(int len, char *buf)
 {
@@ -315,5 +317,3 @@ GenerateRandomData(int len, char *buf)
     close(fd);
 #endif
 }
-
-#endif                          /* XCSECURITY */