Introduced global swith BUILD_SHARED_LIBS; configure will fail hard if the build targets require shared libs and BUILD_SHARED_LIBS is set to OFF
libdl dependency only applies when building the whole ERT application
Changed handling of libdl: Will look for it - and if found look for dladdr(); if not found: util_abort_simple()
More libdl updates
Merge pull request #181 from joakim-hove/static-linux-build

Introduced global swith BUILD_SHARED_LIBS