[Gc] OpenBSD

[Taylan Ulrich B.]

Hi Ivan,

I tried all 7.2 releases, and misc.c won't compile with any of them.
Alpha6 comes close. I added a #define for GC_ATTR_UNUSED and only the
following errors remain.

misc.c:1536: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'GC_on_abort'
misc.c:1538: error: expected ')' before 'fn'
misc.c:1547: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'GC_get_abort_func'
misc.c:1836: error: expected ')' before 'fn'
misc.c:1845: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'GC_get_on_heap_resize'

I don't know how easy these are to fix, and don't have time left today,
so just sending this off before heading away.

Regards,
Taylan