handle non-fatal errors on SSLRead

[ragoso]

From #182

Based on curl's solution on this issue and PR

[kornelski]

I'm worried about continuing on errSSLWouldBlock. You get this with non-blocking sockets, so next read will very likely return the same error, and since you're calling read recursively, this can blow up the stack (and if it didn't, it'd be busy-looping).

[ragoso]

I'm worried about continuing on errSSLWouldBlock. You get this with non-blocking sockets, so next read will very likely return the same error, and since you're calling read recursively, this can blow up the stack (and if it didn't, it'd be busy-looping).

You're right, let's just stop at the root cause.