configure: add additional flags to LDFLAGS on OS/2

This allows to build a DLL and to open files in binary mode.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

configure.ac

@@ -55,6 +55,9 @@ AC_C_BIGENDIAN
 AS_CASE([$host],
   [*mingw32* | *cygwin*], [AC_CHECK_FUNCS(gettimeofday)])
 
+AS_CASE([$host],
+  [*os2*], LDFLAGS="-no-undefined -Zbin-files $LDFLAGS")
+
 AC_ARG_WITH([libdvdcss],
   AS_HELP_STRING([--with-libdvdcss], [Link directly against libdvdcss @<:@default=no@:>@]))