Suppress leak detector in some cases

Suppress leak detector in some cases

We intentionally leak some objects.  Prevent the ASan leak detector
from raising false alarms in these cases.

* configure.ac: Search for lsan_interface.h header.

* src/data.c (make_blv): Allow leaking of buffer-local values.

* src/buffer.c (enlarge_buffer_text): Allow leaking of buffer text.

* src/emacs-module.c (Fmodule_load, initialize_environment): Allow
intentional leak of runtime and environment objects if module
assertions are enabled.