Declare __fake_use_va_args as a variadic function.

* New clang compiler requires variadic function to have
  at least one named parameter type.
* Use ##__VA_ARGS__ to work with empty __VA_ARGS__.
* Fix one ALOG_ASSERT parameter bug in lmkd/lmkd.c.

Bug: 111614304
Test: make with WITH_TIDY=1
Change-Id: I90f35aa88527a6897954f69a35b256a157a725c5