runpath for X11 in autotools?

[ng0]

Hi,

with my next commit this is required for me on a system without
/etc/ld.so.conf to make gnunet-qr link correctly (or rather execute):

make clean-recursive ; ./bootstrap ; LDFLAGS="-L/usr/pkg/lib -L/usr/X11R7/lib 
-Wl,-R/usr/X11R7/lib" CFLAGS="-g -O0" ./configure --prefix=/home/ng0/gnunet 
--enable-logging=verbose
--with-jansson=/usr/pkg --with-zbar=/usr/pkg --with-sm=/usr/X11R7/

is the portable way for autotools for one binary to add this to the LDFLADS in 
the Makefile.am
in the src/util directory, or how is this handled?