split_ncvars.pl has incorrect path for list_ncvars

**Describe the bug**
The default location for list_ncvars.sh in split_ncvars.pl is incorrect.  The path is missing `bin` in the path.  

**To Reproduce**
Build and run split_ncvars.pl on any NetCDF file.  Split_ncvars will not create the split NetCDF files.

**Expected behavior**
Split_ncvars should create a set of files, one variable per file.
