Change LSM_ERR_LIB_BUG to LSM_ERR_PLUGIN_BUG
Change LSM_ERR_LIB_BUG to LSM_ERR_PLUGIN_BUG

In most cases if we fall into this error case, it's because the
serialized json was wrong which is more likely to be because of
a plugin returning something incorrect, rather than the library
itself.

Signed-off-by: Tony Asleson <1ef2d381aa56d512126ddaacc29e68136e4fdf55@redhat.com>

tasleson/libstoragemgmt,libstorage/libstoragemgmt,jumitche/libstoragemgmt,cathay4t/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,joehandzik/libstoragemgmt,lazy404/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,jumitche/libstoragemgmt,jumitche/libstoragemgmt,libstorage/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,lazy404/libstoragemgmt,libstorage/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,lazy404/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,joehandzik/libstoragemgmt,cathay4t/libstoragemgmt,jumitche/libstoragemgmt,cathay4t/libstoragemgmt,lazy404/libstoragemgmt