[DebugInfo] DIBuilder missing interface to generate DWARF info for packed_decimal basic type.

As Paul mentioned, we're now beginning to work on our COBOL, BASIC, etc.
debug support for OpenVMS.

Our legacy compilers started back with DWARF-2 so all of our tags were
in the vendor-specific area. They mostly became part of DWARF-3. We'll
be using the DWARF-3 names/encodings and change our debugger as needed.

The list of tags we'll be adding (pardon my BLISS syntax) will include:

LITERAL DW_AT_HP_decimal_sign = %X'200a';
LITERAL DW_AT_HP_digit_count = %X'200b';
LITERAL DW_AT_HP_decimal_scale = %X'200c';
LITERAL DW_AT_HP_picture_string = %X'200f';
LITERAL DW_AT_HP_edit_string = %X'2028';

We also have

LITERAL DW_ATE_HP_VAX_float = %X'88';
LITERAL DW_ATE_HP_VAX_float_d = %X'89';
LITERAL DW_ATE_HP_packed_decimal = %X'8a';
LITERAL DW_ATE_HP_zoned_decimal = %X'8b';
LITERAL DW_ATE_HP_edited = %X'8c';
LITERAL DW_ATE_HP_signed_fixed = %X'8d';
LITERAL DW_ATE_HP_unsigned_fixed = %X'8e';
LITERAL DW_ATE_HP_VAX_complex_float = %X'8f';
LITERAL DW_ATE_HP_VAX_complex_float_d = %X'90';

What version of LLVM are you working on? We're currently stuck at 3.4.2
for our cross-compilers due to the host C++ compiler, but will bootstrap
our way to ToT once the native systems are up and stable.

John