v2.21

Bugfixes:

• bin format, absolute segments: if segment wasn't referenced directly,
  but by the SEG operator, invalid code was generated; see absseg4.asm.
• macro arguments: curly braces now handled Masm-compatible; see
  macro25.asm.
• operator MOD returned wrong results for negative operands; see mod1.asm,
  mod2.asm.
• operator '/': 64-bit division generally assumed signed operands, hence
  results were wrong if dividend was unsigned with bit 63 set.
• elf format: in symbol table, size wasn't set for data publics.
• error "initializer magnitude too large" occured if the negative offset
  of a struct member was referenced as 8-bit value; see struct44.asm &
  struct45.asm.
• option -elf64: addends calculation wrong if explicitely defined; see
  elf2.asm.
• model TINY, predefined symbol @code: changed from _TEXT to DGROUP; see
  tinycode.asm.
• TYPE operator: returned values != 0 for certain constants defined with
  EQU; see types18.asm.
• ALIAS directive: alias name wasn't decorated reliably; see alias3.asm.
• non-OMF formats: code buffer was allocated in each pass, causing memory
  leaks.
• fixed GPF in jwasm: assembling MOV instruction with destination of type
  prototype, but without pointer type definition; see pproc.asm.
• fixed buffer overflow in listing if EQU defined an alias in 32/64-bit.

Other changes:

• format elf: cmdline option -Zd (dwarf line numbers) supported (limited
  to one file).
• format elf: added cmdline option -pic{0|1|2}; position-independent code
  generation (-pic1) is now the default for elf.
• format elf: EXTERNDEF accepts optional EXPORT qualifier; this qualifier
  modifies visibility for -pic2.
• format elf32: qualifier SECTIONREL redefined for this format; will
  return offset relative to GOT.
• format elf32: special handling of symbol GLOBAL_OFFSET_TABLE.
• option -pe: .stack directive will set reserved stack space in PE header.
• option -?: exit with errorcode 0 instead of 1.
• format coff: in listing, COMDAT attr. (segments and symbols) is rendered.
• listing: don't print language for non-public items in symbol table.
• extension ASSUME USExx added to (temporarily) switch bitness inside a
  segment; see assumex1.asm.