os: fix tests on brillo
os: fix tests on brillo

Not every Android contains the /system/framework directory, e.g. Brillo.
Test against other Android-only system files.

Fixes #14489.

Change-Id: I6d9ec1c4d4ceba3803798015e6917d59cf515de8
Reviewed-on: https://go-review.googlesource.com/19904
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Burcu Dogan <347c19a639ce752a783b4ea325d6539ab4b4a262@google.com>
Run-TryBot: Burcu Dogan <347c19a639ce752a783b4ea325d6539ab4b4a262@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

linux-on-ibm-z/go,akutz/go,Cofyc/go,theif519/go,josharian/go,binarycrusader/go,mwhudson/go,polyverse-security/go,vsekhar/elastic-go,CAFxX/go,codestation/go,josharian/go,momchil-velikov/go,vsekhar/elastic-go,derekmarcotte/go,linux-on-ibm-z/go,derekmarcotte/go,miolini/go,goodlang/good,derekmarcotte/go,4ad/go,goodlang/good,ImJasonH/go,ganboing/go-esx,CAFxX/go,akutz/go,CAFxX/go,derekmarcotte/go,josharian/go,josharian/go,miolini/go,theif519/go,binarycrusader/go,4ad/go,4ad/go,CAFxX/go,goodlang/good,christopher-henderson/Go,akutz/go,codestation/go,cloudflare/go,nawawi/go,goodlang/good,mwhudson/go,Samurais/go,golang/go,theif519/go,binarycrusader/go,suncycheng/go,akutz/go,4ad/go,linux-on-ibm-z/go,nawawi/go,miolini/go,binarycrusader/go,josharian/go,4ad/go,theif519/go,cloudflare/go,golang/go,vanloswang/go,codestation/go,nawawi/go,suncycheng/go,codestation/go,theif519/go,cloudflare/go,vanloswang/go,goodlang/good,golang/go,vanloswang/go,suncycheng/go,goodlang/good,theif519/go,binarycrusader/go,linux-on-ibm-z/go,vanloswang/go,cloudflare/go,vanloswang/go,ganboing/go-esx,goodlang/good,Samurais/go,CAFxX/go,momchil-velikov/go,suncycheng/go,miolini/go,polyverse-security/go,binarycrusader/go,Samurais/go,polyverse-security/go,linux-on-ibm-z/go,ganboing/go-esx,4ad/go,derekmarcotte/go,vsekhar/elastic-go,nawawi/go,golang/go,ImJasonH/go,Samurais/go,CAFxX/go,Samurais/go,akutz/go,ImJasonH/go,vsekhar/elastic-go,suncycheng/go,Cofyc/go,codestation/go,miolini/go,mwhudson/go,josharian/go,Cofyc/go,golang/go,vsekhar/elastic-go,nawawi/go,akutz/go,polyverse-security/go,cloudflare/go,binarycrusader/go,momchil-velikov/go,ImJasonH/go,momchil-velikov/go,theif519/go,derekmarcotte/go,golang/go,linux-on-ibm-z/go,Samurais/go,cloudflare/go,ganboing/go-esx,mwhudson/go,derekmarcotte/go,CAFxX/go,momchil-velikov/go,ganboing/go-esx,miolini/go,cloudflare/go,ImJasonH/go,ImJasonH/go,4ad/go,CAFxX/go,polyverse-security/go,suncycheng/go,akutz/go,Cofyc/go,suncycheng/go,golang/go,josharian/go,suncycheng/go,polyverse-security/go,mwhudson/go,Cofyc/go,ImJasonH/go,mwhudson/go,Cofyc/go,nawawi/go,golang/go,momchil-velikov/go,Cofyc/go,ganboing/go-esx,4ad/go,vanloswang/go,nawawi/go,mwhudson/go,akutz/go,vsekhar/elastic-go,momchil-velikov/go,ImJasonH/go,linux-on-ibm-z/go,binarycrusader/go,miolini/go,linux-on-ibm-z/go,vsekhar/elastic-go,polyverse-security/go,codestation/go,josharian/go,Samurais/go,ganboing/go-esx,nawawi/go,vanloswang/go,codestation/go,Samurais/go,momchil-velikov/go,Cofyc/go,cloudflare/go,goodlang/good,codestation/go,ganboing/go-esx,vsekhar/elastic-go,mwhudson/go,miolini/go,derekmarcotte/go,polyverse-security/go,vanloswang/go,theif519/go