Improve *OS type libraries

Following up with #2735 "early" resolution, I'd like Vector35 to consider bringing more love to *OS types in embedded type libraries or, alternatively, I could dig a reliable solution to get there "automagically".

Basically, I'd like to no longer have to import standard C types a target would need like this:

The type library would contains at least platform SDK includes that are stable enough, ex: curl/curl.h, unistd.h, etc.

I'd also expect such a library — or tool — to handle #define'd constants. For example, this:

#if __DARWIN_C_LEVEL >= __DARWIN_C_FULL
#define _CS_DARWIN_USER_DIR         65536
#define _CS_DARWIN_USER_TEMP_DIR        65537
#define _CS_DARWIN_USER_CACHE_DIR       65538
#endif /* __DARWIN_C_LEVEL >= __DARWIN_C_FULL */

Would become a "Binary Ninja enumerations" like that:

#pragma mark - unistd.h

// confstr(3)
enum conf_vars: int {
    _CS_DARWIN_USER_DIR = 65536,
    _CS_DARWIN_USER_TEMP_DIR = 65537,
    _CS_DARWIN_USER_CACHE_DIR = 65538,
};

And while we are here, I would be thrilled to also have open-source C and C++ types for *OS, like CommonCrypto/CommonCrypto.h, and SDK headers from Foundation / CoreFoundation, IOKit, etc..

That would be neat.

Read #2735 first, then compare the embedded type-library request with the named headers curl/curl.h, unistd.h, and Apple SDK headers. Done means defining an implementation path for *OS libraries that also represents the requested #define constants and C/C++ types; the issue names no files or tests to run.