Remove cranelift from sys-default feature

When using the Wasmer-WASI crate, the sys-default feature from
wasmer is depending upon, which causes the following to conflict:

[dependencies.wasmer]
version = "2.0"
default-features=false
features=["sys" , "compiler-singlepass", "engine-universal"]

[dependencies.wasmer-wasi]
version = "2.0"

Because wasmer-wasi "2.0" depends on wasmer with the default features,
which implies using cranelift, which conflicts with singlepass.

Fixes #2882

lib/wasi/Cargo.toml

@@ -49,8 +49,31 @@ tracing-wasm = "0.2"
 default = ["sys-default"]
 
 sys = ["wasmer/sys"]
-sys-default = ["wasmer/sys-default", "sys", "logging", "host-fs", "sys-poll", "host-vnet" ]
+sys-default = [
+    "wasmer-min-features",
+    "compiler-cranelift", 
+    "sys", 
+    "logging", 
+    "host-fs", 
+    "sys-poll", 
+    "host-vnet"
+]
 sys-poll = []
+# Minimum required wasmer features for selecting 
+# engine / compiler, combine with one of the 
+# "compiler-*" features to pick your compiler
+#
+# By default, the sys-default feature enables 
+# ["wasmer-min" + "compiler-cranelift"]
+wasmer-min-features = [
+    "wasmer/sys", 
+    "wasmer/wat", 
+    "wasmer/default-universal", 
+    "wasmer/default-compiler",
+]
+compiler-singlepass = ["wasmer/default-singlepass"]
+compiler-cranelift = ["wasmer/default-cranelift"]
+compiler-llvm = ["wasmer/default-llvm"]
 
 js = ["wasmer/js", "mem-fs", "wasmer-vfs/no-time", "getrandom/js", "chrono"]
 js-default = ["js", "wasmer/js-default"]