Fixes for lua regression tests.
Failures happen on systems with lib64 and lib/tri-pl-ets directories.
Fix for examples/subprojects: target install cannot be done in parallel without prior "all"
Fix support for COMPATLIB.
Objects for "features" should not be generated
outside compatibility library.
examples/hello_compatlib: more complex test for COMPATLIBS (fix recent)
Fix bug in examples/hello_compatlib test seen on Linux/glibc-2.19
Fixes for "err" and "warn" features.
Now verr, verrx, vwarn and vwarnx functions are detected correctly with gcc-4.9