Self-host build fails

[ibara]

Hi --

Very trivial diff, not really worth a pull request. Self-host build fails because dwarf.c is missing an #include <stdarg.h> and generates this message:
(src/backend/x86_64/dwarf.c, 108) error: Undefined symbol 'va_list'.

While here, change Makefile -std= to -std=c99, since lacc now defaults to that.
fixes.txt

[larmel]

Thanks, I pushed a fix with the missing include now.
I don't want to change to c99 mode while compiling lacc though, at least not yet. It is intentionally written in c89 for maximum portability.

[ibara]

No worries! Sounds good, thanks.