tools: drop bogus and obsolete ptyfuncs.m4

According to openpty(3) it is required to include <pty.h> to get the
prototypes for openpty() and login_tty(). But this is not what the
function AX_CHECK_PTYFUNCS actually does. It makes no attempt to include
the required header.

The two source files which call openpty() and login_tty() already contain
the conditionals to include the required header.

Remove the bogus m4 file to fix build with clang, which complains about
calls to undeclared functions.

Remove usage of INCLUDE_LIBUTIL_H in libxl_bootloader.c, it is already
covered by inclusion of libxl_osdep.h.

Remove usage of PTYFUNCS_LIBS in libxl/Makefile, it is already covered
by UTIL_LIBS from config/StdGNU.mk.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

config/Tools.mk.in

@@ -31,8 +31,6 @@ PTHREAD_CFLAGS      := @PTHREAD_CFLAGS@
 PTHREAD_LDFLAGS     := @PTHREAD_LDFLAGS@
 PTHREAD_LIBS        := @PTHREAD_LIBS@
 
-PTYFUNCS_LIBS       := @PTYFUNCS_LIBS@
-
 LIBNL3_LIBS         := @LIBNL3_LIBS@
 LIBNL3_CFLAGS       := @LIBNL3_CFLAGS@
 XEN_TOOLS_RPATH     := @rpath@