Support alternate file path lists for loading libs

Support alternate file path lists for loading libs

Add a new constructor to the dynamic library
loader helper class that allows callers to specify
more than one path for the desired library. The
ordered, NULL-terminated array of paths is walked
until loading one succeeds. The intention here is
to support both versioned and unversioned file
names for portability across operating systems
with different library naming conventions, e.g:

  { libfoo.so.3, libfoo.so, DE_NULL }

Should load "libfoo" on both Linux and BSD OSs.

Components: Framework

Change-Id: I1a0e1c055dd6eeee8e091be5148b99f1f63d86f6