This PR fixes various issues related to portability to 64-bit compilers, including apple clang.
Header-only libraries.
ArduinoJsonX, WebCam and flatbuffers do not contain any source code to compile to an archive library.
The GNU linker is tolerant of this, but not so with other linkers.
These must set COMPONENT_LIBNAME=0 so archive isn't created.
Patch serialllib.
O_NDELAY is not portable, an alias for O_NONBLOCK which is.
bzero is obsolete, use memset.
Fix sockets strerror_r (also used in IFS library, fix in #2224).
Issue is same function with different return signature.
Can use std::gcd with C++17. Prior to this needed __gcd which is not portable.
This PR fixes various issues related to portability to 64-bit compilers, including apple clang.
COMPONENT_LIBNAME=0so archive isn't created.std::gcdwith C++17. Prior to this needed__gcdwhich is not portable.