convert many if_marked htab to hash_table

convert many if_marked htab to hash_table

ada/

	* gcc-interface/decl.c, gcc-interface/utils.c: replace htab with
	hash_table.

cp/

	* cp-objcp-common.c: Use hash_table instead of htab.

gcc/

	* config/i386/i386.c, function.c, trans-mem.c, tree-core.h,
	tree.c, tree.h, ubsan.c, varasm.c: Use hash_table instead of htab.

From-SVN: r217867