No Default_Initial_Condition check should be generated for an object
declaration that has an explicit initial value. Previously this was
implemented by testing the Has_Init_Expression flag, but this only works
if the object declaration was created by the parser (since only the
parser sets that attribute, at least currently).

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

gcc/ada/

	* exp_ch3.adb
	(Expand_N_Object_Declaration): In deciding whether to emit a DIC
	check, we were previously testing the Has_Init_Expression flag.
	Continue to test that flag as before, but add a test for the
	syntactic presence of an initial value in the object declaration.
	This new test would not supersede the old test in the case where
	an explicit initial value has been eliminated as part of some tree
	transformation.