BUG: workaround for dlclose issue #418

Avoid
Inconsistency detected by ld.so: dl-close.c: 737: _dl_close: Assertion
`map->l_init_called' failed!
when unloading application in the ApplicationEngine framework

This error is seen on Linux platform with gcc >= 4.5
and appears to be caused by STB_GNU_UNIQUE symbols
in the LineSegmentDetection application, a recent gcc feature.

nm otbapp_LineSegmentDetection.so | grep " u "
shows that these symbols comes from the use of Boost.Math
in Code/FeatureExtraction/otbLineSegmentDetector.txx
to compute some mathematical special functions values.

Those special functions are actually provided by netlib/slantec
in the ITK Utilities.