Fix new clang warnings.

Fix new clang warnings.

2019-08-27  Martin Liska  <mliska@suse.cz>

	* cgraph.c (cgraph_node::remove): Remove dead assignment before
	loop.
	* config/i386/i386-features.c (scalar_chain::emit_conversion_insns):
	Enclose in anonymous namespace.
	* config/i386/x86-tune-costs.h (struct processor_costs): Wrap
	hard_register initialization in braces.
	* tree-vrp.h (value_range_base::supports_type_p): Return false
	for function with boolean return type.

From-SVN: r274945