MB-46922 Use erl.exe on Windows
MB-46922 Use erl.exe on Windows

An error was incorrectly printed as the existence of erl was being
checked instead of erl.exe for Windows. It still executes the
correct command as Windows does not require the extension.

Change-Id: I114169c91b6b1bfda49832eac06dab510070a325
Reviewed-on: http://review.couchbase.org/c/couchbase-cli/+/159781
Reviewed-by: Asad Zaidi <24cb9a138ff77fbb3620ec06e7db9a554d50a8f0@couchbase.com>
Reviewed-by: James Lee <d8c596dede5f1eea3b1030b95e7922790d6e257e@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

couchbase/couchbase-cli,couchbase/couchbase-cli