[Fuchsia] Add LLDB options to stage 1 cmake.

LLVM_ENABLE_PROJECTS is automatically forwarded from stage 1 builds to
stage 2 builds, so setting FUCHSIA_ENABLE_LLDB has no effect on
two-stage builds.

Instead, add FUCHSIA_ENABLE_LLDB to the stage one build as well.

This also disables curses and libedit by default for now in both stage1
and stage 2 builds; these should be opt-in.

Reviewed By: haowei

Differential Revision: https://reviews.llvm.org/D145449