gn2bp: add //base linker scripts

There is currently no support in GnUtils for linker scripts (though, it
wouldn't be hard to add, so we should totally do that in the future).

Test: m cronet_aml_components_cronet_android_cronet
Change-Id: I84f7a084501e689d46b48951bb06b6e6be3c5883
2 files changed