[CMake][profile] Don't use `TARGET lld` to avoid ordering issues

Depending on the order in which lld and compiler-rt projects are
processed by CMake, `TARGET lld` might evaluate to `TRUE` or `FALSE`
even though `lld-available` lit stanza is always set because lld is
being built. We check whether lld project is enabled instead which
is used by other compiler-rt tests.

The ideal solution here would be to use CMake generator expressions,
but those cannot be used for dependencies yet, see:
https://gitlab.kitware.com/cmake/cmake/-/issues/19467

Differential Revision: https://reviews.llvm.org/D97256