Check for __android_log_vprint in liblog.

Normally we'd use Android.mk but you can also build for Android using
Cerbero and the autohate build system instead.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

configure.ac

@@ -142,6 +142,7 @@ AS_COMPILER_FLAGS(CFLAGS,
 
 AC_CHECK_FUNC(socket, [], AC_CHECK_LIB(socket, socket, [], AC_ERROR(Cannot find socket() function)))
 AC_CHECK_FUNC(inet_aton, [], AC_CHECK_LIB(nsl, inet_aton, [], AC_ERROR(Cannot find inet_aton() function)))
+AC_CHECK_FUNC(__android_log_vprint, [], AC_CHECK_LIB(log, __android_log_vprint, [], []))
 
 AC_ENABLE_SHARED
 AC_DISABLE_STATIC