Better testing for nc4type.c

[edhartnett]

In libsrc4, nc4type.c is now tied for the lowest percentage of lines tested, at %60. A look at the code coverage shows that some tests can easily be added for this code:

• No test at all for NC4_inq_type_equal().
• Checks for bad inputs when adding types.
• Checks for typesize of atomic types.
• NC4_inq_enum_ident() only checked for some types.
• NC4_put_vlen_element() is not run during testing.

I will take a look at improving this test coverage...

[edhartnett]

With PR #780 test coverage goes up to %74. So good progress but more can be done.

[edhartnett]

Many more tests merged.