pkg/build: remove goma for fuchsia build
pkg/build: remove goma for fuchsia build

We no longer build fuchsia with goma. We might add support for it later
on.

google/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller