Expand BinAssignExp macros in expression.h
fix ElfObj::common_block size

- fix Issue 11237

- Need to explicitly pass the size of the defined common
  symbol as it can't be computed from the symbol type.
struct initializer are not weak symbols

- fix Issue 11237

- The function outdata will take care of the
  BSS optimization for DTallzeros.
add test case for Issue 11237

- fix OS name of linux in Makefile
fix Issue 11226 - Problems with typeof(null) and const
Merge pull request #2701 from dawgfoto/fix11237

fix Issue 11237
fix Issue 11404 - ICE on using TypeTuple for AA values
fix Issue 10015 - Segfault on forward referencing a variable of templated struct
fix Issue 11423 - Error: new can only create structs, dynamic arrays or class objects, not _error_'s
fix Issue 11424 - typedef on structs isn't caught

It should be caught even if the typedef keyword usage is meaningless.
Merge pull request #2710 from 9rnsr/fix11423

Issue 11423 - Error: new can only create structs, dynamic arrays or class objects, not _error_'s
fix Issue 11426 - Reinterpret element-wise array initializing should be rejected
Remove Tascii and replace with Tchar
Remove redundant extern declarations.
Merge pull request #2707 from 9rnsr/fix11404

Issue 11404 - ICE on using TypeTuple for AA values
Merge pull request #2711 from 9rnsr/fix11424

[REG2.064a] Issue 11424 - typedef on structs isn't caught
Merge pull request #2708 from 9rnsr/fix10015

Issue 10015 - Segfault on forward referencing a variable of templated struct
Merge pull request #2703 from 9rnsr/fix11226

Issue 11226 - Problems with typeof(null) and const
fix Issue 11291 - Disallow mutation of a const variable
Merge pull request #2678 from 9rnsr/fix11291

Issue 11291 - Disallow mutation of a const variable