Make verror extern(C) so it can be written in D and called from C++, even though va_list has a different type in dmc and dmd
Refactor macros in arrayop.c
Merge pull request #2045 from yebblies/va_list

[DDMD] Make verror extern(C)
Merge pull request #2237 from yebblies/expandm

[DDMD] Expand macros in arrayop.c