fall back to checking location relative to 'eb' location in find_eb_script

[boegel]

fix for #2247

[pescobar]

the fix seems to work, thanks @boegel !

[easybuild@895087d165c1 ~]$ eb /tmp/generic_centos7/BamTools/BamTools-2.4.0-goolf-1.7.20.eb --try-toolchain=dummy,"" -r /tmp/generic_centos7/ --experimental --rpath
== temporary log file in case of crash /tmp/easybuild/tmp/eb-N7ICqj/easybuild-B0WPNn.log
== resolving dependencies ...
== processing EasyBuild easyconfig /tmp/easybuild/tmp/eb-N7ICqj/tweaked_dep_easyconfigs/CMake-2.8.12.eb
== building and installing CMake/2.8.12...
== fetching files...
== creating build dir, resetting environment...
== unpacking...
== patching...
== preparing...
== configuring...
== building...
== testing...
== installing...
== taking care of extensions...
== postprocessing...
== sanity checking...
== cleaning up...
== creating module...
== permissions...
== packaging...
== COMPLETED: Installation ended successfully
== Results of the build can be found in the log file(s) /easybuild/apps/CMake/2.8.12/easybuild/easybuild-CMake-2.8.12-20170629.110721.log
== processing EasyBuild easyconfig /tmp/easybuild/tmp/eb-N7ICqj/tweaked_easyconfigs/BamTools-2.4.0.eb
== building and installing BamTools/2.4.0...
== fetching files...
== creating build dir, resetting environment...
== unpacking...
== patching...
== preparing...
== configuring...
== building...
== testing...
== installing...
== taking care of extensions...
== postprocessing...
== sanity checking...
== cleaning up...
== creating module...
== permissions...
== packaging...
== COMPLETED: Installation ended successfully
== Results of the build can be found in the log file(s) /easybuild/apps/BamTools/2.4.0/easybuild/easybuild-BamTools-2.4.0-20170629.110736.log
== Build succeeded for 2 out of 2
== Temporary log file(s) /tmp/easybuild/tmp/eb-N7ICqj/easybuild-B0WPNn.log* have been removed.
== Temporary directory /tmp/easybuild/tmp/eb-N7ICqj has been removed.

The rpath linking seems to work properly:

[easybuild@895087d165c1 ~]$ ml
No modules loaded

[easybuild@895087d165c1 ~]$ ldd /easybuild/apps/BamTools/2.4.0/bin/bamtools|grep easybuild
	libbamtools.so.2.4.0 => /easybuild/apps/BamTools/2.4.0/bin/../lib/libbamtools.so.2.4.0 (0x00007fbd6d16c000)

[boegel]

@wpoely86 please review?

[boegel]

Thanks for the review @wpoely86!