[newlib-cygwin] Cygwin: select: revamp non-polling code for signalfd

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=7097b05eda2f8e9058eab4fda8dedacdfb7ffd7f commit 7097b05eda2f8e9058eab4fda8dedacdfb7ffd7f Author: Corinna Vinschen Date: Fri Aug 16 16:36:06 2019 +0200 Cygwin: select: revamp non-polling code for signalfd Rather than

[newlib-cygwin] Revert "Cygwin: fix potential SEGV in sigwaitinfo/signalfd scenario"

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b7399d5e6f8ad5b15cd725f66b3e49732393ef03 commit b7399d5e6f8ad5b15cd725f66b3e49732393ef03 Author: Corinna Vinschen Date: Fri Aug 16 16:36:20 2019 +0200 Revert "Cygwin: fix potential SEGV in sigwaitinfo/signalfd scenario"