This fixes two problem:

1. an omitted --build-lib library could yield strange grep errors. For
   instance, calling build_oai --build-lib --cmake-opt OPTION passed
   "--cmake-opt" to grep, that does not know this option. Handle by
   explicitly separating options and search pattern through --.
2. Even with this fixed, set -e triggered an exit because grep exits
   with non-zero error code. Remove set -e to have the error handling
   code pass.

With set -e removed, properly check that the build passes.

Update a log line to make it clearer.

Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Robert Schmidt <robert.schmidt@openairinterface.org>