maint: improve error messages upon failed read, write, access, close

maint: improve error messages upon failed read, write, access, close

Note we use "failed to {access,close}" for those single operations,
and "error {read,writ}ing" for those partial operation failures.

* src/copy.c: Improve error messages for failing read, write and close.
* src/cp.c: Improve error messages for failing access.
* src/dd.c: Improve error messages for failing read, write and open.
* src/head.c: Improve error message for failing close.
* src/install.c: Improve error messages for failing access.
* src/ln.c: Likewise.
* src/mv.c: Likewise.
* src/touch.c: Improve error message for failing close.
* src/truncate.c: Likewise.