cygport: patch for proper debuginfo

[Marco Atzeri via Cygwin-apps]

In some conditions the debuginfo creation enters in a never ending loop
due to the asymmetrical usage of readlink between

lib/src_postinst.cygpart :

     origdlname=${dlname}
     while [ $(readlink -f ${ltlibdir}/${dlname%/bin/*}) != 
${D}$(__host_prefix) ]
      do
              dlname=../${dlname}
      done


and bin/cygport.in:
               _topdir=.;


This happens when the directory of building has a link in one
of the parent directories

$ pwd
/pub/devel/openblas

$ readlink -f .
/cygdrive/d/cyg_pub/devel/openblas

Regards
Marco
diff --git a/bin/cygport.in b/bin/cygport.in
index 1fe804d..2eeff26 100755
--- a/bin/cygport.in
+++ b/bin/cygport.in
@@ -397,7 +397,7 @@ if [ "x${_topdir}" = "x${argv[1]}" ]
 then
        if [ -f ./${cygportfile} ]
        then
-               _topdir=.;
+               _topdir=$(readlink -f .);
        else
                _topdir=/usr/src;
        fi