ffi/unsafe/custodian: doc clarifications
pkg/path: fix `pkg-info` contract in docs
reference: fix docs for octal character literal

Bug reported by Emmanuel Schanzer
fix problem with truncated value printing and stack overflow

A value-printing truncation discovered after a stack-overflow handle
and return could go badly, because the truncation escape wasn't
reset correctly after overflow handling (in contrast to truncation
discovered during the overflow handling, which was handled correctly).

Closes PR 14870
pkg/path: fix problems with `path->pkg` and case or nonexistent

The `path->pkg` funciton shouldn't return the name of a package that
isn't installed, including a case-folded version of a package that is
installed. On Windows, where we match case-normalized paths, we have
to work a little harder to map a case-normalized path element to the
installed package name, given that package names are case-sensitive.

Closes PR 14861
raco pkg: less noisy about consulting local catalogs

The "Resolving..." status reports are meant mainly to indicate when
network access is happening. Don't print in advance when a local
catalog is being used, but do print when a local catalog provided the
answer.