The current practice of copying the perfetto.cc/h files seems to be in contradiotion with what meson supports

[gerddie]

When I run meson on percetto, I get an error

Message: Perfetto SDK: /home/gerddie/src/Collabora/virgl-gitlab/build-percetto/../subprojects/perfetto-sdk
|../subprojects/percetto/perfetto-sdk/meson.build:45: WARNING: Custom target input '['/home/gerddie/src/Collabora/virgl-gitlab/build-percetto/../subprojects/perfetto-sdk/perfetto.cc', '/home/gerddie/src/Collabora/virgl-gitlab/build-percetto/../subprojects/perfetto-sdk/perfetto.h']' can't be converted to File object(s).
|This will become a hard error in the future.

So in the future this method of just copying the files over will no longer work.

[olvaffe]

We don't really need input:. This is a "codegen" target, and we know how to codegen from just the sdk path.