Implement ID creation optimization for container datatype conversions (#4113)

Makes the datatype conversion context object available during both the
initialization and conversion processes for a datatype conversion
function, allowing the compound, variable-length and array datatype
conversion functions to avoid creating IDs for the datatypes when they
aren't necessary

Adds internal H5CX_pushed routine to determine if an API context is
available to retrieve values from

Also adds error checking to several places in H5T.c and H5Tconv.c where
the code had previously assumed object close operations would succeed

0 files changed, 0 insertions, 0 deletions