re PR middle-end/78548 (ICE on valid C code on x86_64-linux-gnu at -O2 and -O3 in 64-bit mode with -Wall (*** Error in `/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/cc1': double free or corruption (fasttop): 0x0000000003c15810 ***))

	PR middle-end/78548
	* tree-ssa-uninit.c (simplify_preds_4): Call release() instead of
	destroy_predicate_vecs.
	(uninit_uses_cannot_happen): Make uninit_preds a scalar.

From-SVN: r243289