vim: Fix an indentation issue with cindent

cindent handles the following case incorrectly:

impl X {
    b: int,
    //
    c: int,
}

if you try and insert a new line after the `c` declaration.

To fix this, fix the get_line_trimmed() function to work properly, and
then extend GetRustIndent to keep searching backwards until it finds a
non-blank line after trimming. This lets it handle the trailing comma
case properly, as if the comment were never there.

Fixes #14041.
serialize: Ignore two flaky json tests on windows

See #14064 for some rationale, but the basic idea is that I suspect that there
is an LLVM codegen bug somewhere, and I'm not entirely sure why it's happening
intermittently rather than deterministically...

cc #14064
Rename Pod to Copy

Some error messages still use the word `Pod` instead of `Copy`. Renames
them.
auto merge of #14065 : alexcrichton/rust/ignore-flaky-windows-test, r=brson

See #14064 for some rationale, but the basic idea is that I suspect that there
is an LLVM codegen bug somewhere, and I'm not entirely sure why it's happening
intermittently rather than deterministically...

cc #14064
auto merge of #14056 : kballard/rust/vim_indent_fix, r=huonw

cindent handles the following case incorrectly:

    impl X {
        b: int,
        //
        c: int,
    }

if you try and insert a new line after the `c` declaration.

To fix this, fix the get_line_trimmed() function to work properly, and
then extend GetRustIndent to keep searching backwards until it finds a
non-blank line after trimming. This lets it handle the trailing comma
case properly, as if the comment were never there.

Fixes #14041.
auto merge of #14066 : edwardw/rust/pod-to-copy, r=alexcrichton

Some error messages still use the word `Pod` instead of `Copy`. Renames
them.