Extend libtool RPATH outsmarting hack to external/coinmp's CoinUtils

(See 1d028d47 "Fix Linux RPATH of various
external modules" for the original external/coinmp/rpath.patch missing a patch
for CoinUtils/configure.)  This is a blind fix attempt for
<https://ci.libreoffice.org/job/lo_daily_update_gandalf/559/console>

> /lo/home/tdf/lode/jenkins/workspace/lo_daily_update_gandalf/instdir/program/libCoinUtils.so.3 has unexpected RPATH  0x000000000000001d (RUNPATH)            Library runpath: [/opt/rh/devtoolset-7/root/usr/lib/../lib64:$ORIGIN]
> /lo/home/tdf/lode/jenkins/workspace/lo_daily_update_gandalf/postprocess/CustomTarget_check_dynamic_objects.mk:20: recipe for target '/lo/home/tdf/lode/jenkins/workspace/lo_daily_update_gandalf/workdir/CustomTarget/postprocess/check_dynamic_objects/check.done' failed

after ed81fe44 "Enabling Developer Toolset 7 for
Jenkins' remaining GCC master jobs" enabled GCC 8 at gandalf's
/opt/rh/devtoolset-7/root/ (which is at the same location as a CentOS Developer
Toolset 7 special GCC 7, but is actually a plain GCC 8, cf.
<https://lists.freedesktop.org/archives/libreoffice/2018-December/081544.html>
"Re: Compiler baselines") for the lo_daily_update_gandalf job.  Presumably
libtool added to RPATH a path to find that GCC 8 installation's
/opt/rh/devtoolset-7/root/usr/lib64/libstdc++.so.6.

Change-Id: I37c98faffe3e6c014e321b756a18a8468c32877c
Reviewed-on: https://gerrit.libreoffice.org/64942
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/coinmp/rpath.patch

@@ -38,6 +38,16 @@
      ;;
    lynxos*)
      # FIXME: insert proper C++ library support
+--- CoinUtils/configure
++++ CoinUtils/configure
+@@ -13939,6 +13939,7 @@
+ 	output_verbose_link_cmd='templist=`$CC -shared $CFLAGS -v conftest.$objext 2>&1 | grep "ld"`; templist=`echo $templist | $SED "s/\(^.*ld.*\)\( .*ld .*$\)/\1/"`; list=""; for z in $templist; do case $z in conftest.$objext) list="$list $z";; *.$objext);; *) list="$list $z";;esac; done; echo $list'
+ 	;;
+     esac
++hardcode_libdir_flag_spec_CXX=
+     ;;
+   lynxos*)
+     # FIXME: insert proper C++ library support
 --- Osi/configure
 +++ Osi/configure
 @@ -12453,6 +12453,7 @@