The reworking of the gdb client tests into the PlatformClientTestBase broke
the test for this. I did the mutatis mutandis for the move, but the test
still fails. Reverting till I have time to figure out why.
This reverts commit b715b79d54d5ca2d4e8c91089b8f6a9389d9dc48.
We don't actually need a local copy of the main executable to debug
a remote process. So instead of treating "no local module" as an error,
see if the LaunchInfo has an executable it wants lldb to use, and if so
use it. Then report whatever error the remote server returns.
Differential Revision: https://reviews.llvm.org/D113521