Fix SIGSEGV in eloop during shutdown

Fix SIGSEGV in eloop during shutdown

eloop_destroy() frees the eloop.signals array but was not unregistering
the signal handlers. A signal received during shutdown could trigger
eloop_handle_signal(), accessing the freed memory and causing a crash
(Use-After-Free).

This fix unregisters all signals (resets to SIG_DFL) in eloop_destroy()
before freeing eloop.signals to ensure safe shutdown.

Signed-off-by: Priyansha Tiwari <pritiwa@qti.qualcomm.com>