mount information is now sorted in order of descending mount
point lengths to fix a bug in matching file names to mount
points. the longest mount point string which matches the file
name is the corresponding mount. this change requires slight
changes to the darshan-logutils API, but does not modify the
log file format

Otherwise, compile errors are generated when building an external
tool that uses the darshan-logutils api/library.

Darshan now provides debugging tips for cases where log files
are not generated.

Since we had to modify HDF5/PnetCDF linker flags to work on Cray
by undefining appropriate symbols, we need to update the linker
options used in darshan-config. darshan-config linker options need
to include the stubs libraries and use '--start-group' and
'--end-group' flags to resolve the symbols correctly

moved most test programs and previous darshan output
to the 2.x directory

this reorganization prevents darshan from being "enabled"
(i.e., accessible to modules) until the initialization
has completely finished.