Add no-export in cbindgen.toml config

[tisonkun]

@aidanhs @emilio

I need it for my c binding of OpenDAL and local tests pass with this change.

Let me know if this patch needs some improvement :D

[tisonkun]

It seems that for Style::Tag and Language::C, my work case can pass. But the test coverage also check for other style and language like pyx. The previous no-export attr should share the same issue.

@emilio what would you suggest to write a test? I cannot write a proper test for it but it's the same as when we previously merge "no-export` attr.

[emilio]

It seems that for Style::Tag and Language::C, my work case can pass. But the test coverage also check for other style and language like pyx. The previous no-export attr should share the same issue.

@emilio what would you suggest to write a test? I cannot write a proper test for it but it's the same as when we previously merge "no-export` attr.

For tests, you can include relevant boilerplate using config.header or so to make the test files compile, right? We do that in a bunch of tests.