Cranelift: add a config option for alias analysis and redundant-load elimination. (#4349)

This allows for experiments as in here [1] and also generally gives an
option to anyone who is concerned that the extra optimization may be
counterproductive or take too much time. The optimization remains
enabled by default.

[1]
https://github.com/bytecodealliance/wasmtime/pull/4163#issuecomment-1169303683

cranelift/codegen/src/settings.rs

@@ -516,6 +516,7 @@ libcall_call_conv = "isa_default"
 baldrdash_prologue_words = 0
 probestack_size_log2 = 12
 regalloc_checker = false
+enable_alias_analysis = true
 enable_verifier = true
 is_pic = false
 use_colocated_libcalls = false