* replace darwin checks in extconf.rb to exclude TruffleRuby
* inherit RANLIB and STRIP from RbConfig, set LDXX
* enable overriding ranlib command in top-level makefile
* ensure the -no_warning_for_no_symbols flag is only used with Apple's ranlib
* don't embed openssl & zlib on truffleruby
* add RbConfig's cppflag to CPPFLAGS when using TruffleRuby
* this ensure the paths to find the system's OpenSSL are set up correctly with TruffleRuby (includes being able to find an OpenSSL installed via Homebrew etc)
* don't statically link standard libraries on Linux with Truffleruby
* This does not work when compiling to bitcode.
* Prefer SIGTERM to SIGQUIT for graceful shutdown in examples
* Overriding SIGQUIT is suboptimal, for example on JVM where it is very
useful to dump the thread stacktraces.
* Keep the rb_tr_abi_version symbol for TruffleRuby in grpc_c.so
* Otherwise TruffleRuby cannot verify the ABI version is correct.
* See https://github.com/oracle/truffleruby/issues/2386
* Use RbConfig::CONFIG['STRIP'] instead of just `strip`
* Use a local variable for apple_toolchain for consistency
* Add a comment about -static-libgcc -static-libstdc++ and TruffleRuby
* Split comment into two for openssl/zlib
Co-authored-by: Nicolas Laurent <nicolas.laurent@oracle.com>