Rollup merge of #66305 - elichai:2019-11-array_ffi, r=eddyb

Add by-value arrays to `improper_ctypes` lint

Hi,
C doesn't have a notion of passing arrays by value, only by reference/pointer.
Rust currently will pass it correctly by reference by it looks very misleading, and can confuse the borrow checker to think a move had occurred.

Fixes #58905 and fixes #24578.

We could also improve the borrow checker here but I think it's kinda a waste of work if we instead just tell the user it's an invalid FFI call.

(My first PR to `rustc` so if I missed some test or formatting guideline please tell me :) )

diff --cc src/librustc_lint/types.rs
Simple merge