Use consistent cpp logic for including backtrace.h
Use consistent cpp logic for including backtrace.h

__linux__ -> __ELF__

apitrace/apitrace,joshua5201/apitrace,EoD/apitrace,apitrace/apitrace,swq0553/apitrace,EoD/apitrace,schulmar/apitrace,joshua5201/apitrace,trtt/apitrace,surround-io/apitrace,tuanthng/apitrace,swq0553/apitrace,joshua5201/apitrace,tuanthng/apitrace,trtt/apitrace,trtt/apitrace,swq0553/apitrace,apitrace/apitrace,surround-io/apitrace,joshua5201/apitrace,schulmar/apitrace,surround-io/apitrace,schulmar/apitrace,tuanthng/apitrace,apitrace/apitrace,tuanthng/apitrace,trtt/apitrace,schulmar/apitrace,EoD/apitrace,surround-io/apitrace,swq0553/apitrace,schulmar/apitrace,EoD/apitrace,trtt/apitrace,EoD/apitrace,swq0553/apitrace,tuanthng/apitrace,surround-io/apitrace,joshua5201/apitrace