Remove lldb-repro which was used to run the test suite against a
reproducer. The corresponding functionality has been removed from LLDB
so there's no need for the tool anymore.
Make it possible to run the script command with a different language
than currently selected.
$ ./bin/lldb -l python
(lldb) script -l lua
>>> io.stdout:write("Hello, World!\n")
Hello, World!
When passing the language option and a raw command, you need to separate
the flag from the script code with --.
$ ./bin/lldb -l python
(lldb) script -l lua -- io.stdout:write("Hello, World!\n")
Hello, World!
Differential revision: https://reviews.llvm.org/D86996
