This fixes issues on Android where applications use these signals in their
normal course of execution. The Mono C# framework uses SIGXCPU for garbage
collection, and ART uses SIGSEGV, SIGQUIT, and SIGUSR1.

Bug 27555932

Change-Id: I4977b8f0419da660a57a8eeef20a7fe747921a63
Reviewed-on: https://swiftshader-review.googlesource.com/5345Reviewed-by: Greg Hartman <ghartman@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>