gprofng not reading references correctly in Dwarf

Fixed as specified in the DWARF standard:
 The first type of reference can identify any debugging information entry
 within the containing unit. This type of reference is an offset from the first
 byte of the compilation header for the compilation unit containing
 the reference. There are five forms for this type of reference.
 There are fixed length forms for one, two, four and eight byte offsets
 (respectively, DW_FORM_ref1, DW_FORM_ref2, DW_FORM_ref4, and DW_FORM_ref8).
 There is also an unsigned variable length offset encoded form that uses
 unsigned LEB128 numbers (DW_FORM_ref_udata).

gprofng/ChangeLog
2025-04-27  Vladimir Mezentsev  <vladimir.mezentsev@oracle.com>

	* src/DwarfLib.cc (set_die): Handling DWARF references (DW_FORM_ref1,
	DW_FORM_ref2, DW_FORM_ref4, DW_FORM_ref8, DW_FORM_ref_udata).
	* src/Dwarf.cc: Likewise.