[PATCH] XDM: Fix FTBFS with gold or recent gcc releases.

[Mark Kettenis]

> Date: Sat, 19 Feb 2011 18:03:04 +0000
> From: Fernando Lemos <fernandotcl at gmail.com>
> 
> /usr/bin/ld: session.o: undefined reference to symbol 'dlclose@@GLIBC_2.2.5'
> /usr/bin/ld: note: 'dlclose@@GLIBC_2.2.5' is defined in DSO
> /lib64/libdl.so.2 so try adding it to the linker command line
> /lib64/libdl.so.2: could not read symbols: Invalid operation
> collect2: ld returned 1 exit status
> make[2]: *** [xdm] Error 1
> 
> Adding AC_SEARCH_LIBS([dlopen], [dl]) solves it, not sure there isn't
> a better way to do it?

Looks like AC_LIBTOOL_DLOPEN does the check for dlopen/-ldl, but
doesn't automatically add it.  You'll need to add @LIBADD_DL@ and/or
$(LIBADD_DL) in the appropriate places.  That's probably a better way
to fix this issue.