Cherrypick lang/go mmap patch...

[sean-]

We should cherrypick the mmap(2) patch that officially landed in Go.

We should replace the contents of https://github.com/joyent/pkgsrc/blob/trunk/lang/go/patches/patch-src_runtime_mem__bsd.go with golang/go@13cdd81

CC @jperkin

[mamash]

Sean, I made this change per your suggestion earlier:

https://github.com/jsonn/pkgsrc/blob/trunk/lang/go/patches/patch-src_runtime_mem__bsd.go

Is it the same fix and will it work until we hit 1.9? I cherry-picked that change over to 2016Q4.

[sean-]

@mamash It's slightly different in that _EAGAIN doesn't exist on the BSDs. The patch that is in place works just fine for Illumos, but I'd rather track what's been officially upstreamed because it's been verified in the official Go test environment.

golang/go@13cdd81#diff-0551b4988cf924970084df57358d1181R62

[mamash]

OK cool, I'll align the patch and make note to drop it with 1.9.

[sean-]

It looks like this was done in d26605e, thanks @mamash