Fix libva related compile errors

- Make h264.c compile with recent libva version by including va_compat.h
- Only enable libva if libva-x11 is installed
- Modified configure help text
  Previous help text suggested libva was only build when --with-libva
  was specified, while actual behavior is to build it by default.

Warning: THIS CODE IS UNTESTED. Lacking a h.264 capable VNC server
Also no attempt is made to support platforms not using X11
Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>

configure.ac

@@ -150,12 +150,11 @@ AM_CONDITIONAL(HAVE_LIBSSL, test ! -z "$SSL_LIBS")
 
 
 # See if we want libva support
-# TODO: check if library actually exists
 AH_TEMPLATE(CONFIG_LIBVA, [Build libva support])
 AC_ARG_WITH(libva,
-[  --with-libva                   build libva support],,)
+[  --without-libva         disable support for libva],,)
 if test "x$with_libva" != "xno"; then
-    AC_CHECK_LIB(va, vaInitialize,
+    AC_CHECK_LIB(va-x11, vaGetDisplay,
         VA_LIBS="-lva -lva-x11"
         [AC_DEFINE(CONFIG_LIBVA) CONFIG_LIBVA="true"], ,)
 fi

libvncclient/h264.c

@@ -20,6 +20,10 @@
 #ifdef LIBVNCSERVER_CONFIG_LIBVA
 
 #include <X11/Xlib.h>
+#include <va/va_version.h>
+#if VA_CHECK_VERSION(0,34,0)
+#include <va/va_compat.h>
+#endif
 #include <va/va_x11.h>
 
 enum _slice_types {