Some android systems like ARM64 may not have the __system_property_get
symbol in libc (but still have it in the public headers). Detect this
condition at build time. The __system_property_get method of retrieving
name servers is deprecated as of Oreo so should strictly be a fallback
mechanism anyhow.
Socklen_t should not be used in code, instead ares_socklen_t should be used.
Convert ssize_t to ares_ssize_t for portability since the public API now exposes this.
The patch does not modify any source files, it only adds 3 new files
(CMakelists.txt, ares_build.h.cmake, ares_config.h.cmake) which form the
build system. I've tried to go through as much of the autotools tests and
extracted what I thought was appropriate, though many of the tests aren't
as in-depth in CMake as they are for autotools ... it is unclear why some
of them exist at all, I'm guessing for legacy systems that CMake probably
doesn't support anyhow.
Building the library, and examples (adig, ahost, acountry) plus installation
should work across a large number of tested platforms. The tests have not
yet been integrated.