518adcca0a: "Try using arm32 implementation for fibers."
dbe232e24e: "Order of arguments might be incorrect in arm32 coroutine implementation."
It seems to cause SEGV consistently on Ubuntu armv7l eabihf:
20190625T081710Z.fail.html.gz
20190625T111708Z.fail.html.gz
It is more conventional to use compiler to pre-process and
assemble the `.S` file rather than forcing Makefile to use `.s`.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65952 b2dd03c8-39d4-4d8f-98ff-823fe69b080e