Expansion of entry families contained a condition that was always true.
Cleanup related to detection of uninitialized scalar objects (which
uncovered that expansion of entry families creates a slightly illegal
AST with Elsif_Parts being an empty list).

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* exp_ch9.adb (Build_Find_Body_Index): Remove IF statement whose
	condition was true-by-construction; remove excessive assertion
	(since the call to Elsif_Parts will check that Nod is present
	and it is an if-statement).