Compiler warnings present when integrated with Swift Package Manager

**Describe the bug**

There are bunch of warnings from `zstd.h` in the following form when compiling:
> Definition of configuration mac 'ZSTDLIB_VISIBLE' has no effect on the import of 'libzstd'; pass '-DZSTDLIB_VISIBLE=...' on the command line to configure the module

It is possible to have these preprocessor definitions in `cSettings` in the `Package.swift` integration site, but that should not be necessary in my opinion and the project should build without warnings.

**To Reproduce**

1. Use library with Swift Package Manager
2. Compile with `swift build`

**Expected behavior**

No warnings should be given.

**Screenshots and charts**


**Desktop (please complete the following information):**
- OS: macOS
- Version 14.2.1
- Compiler swiftc
- Flags n/a
- Other relevant hardware specs n/a
- Build system SPM