Fixes for 0.15 (#1449)

* Wasmtime 0.15.0 and Cranelift 0.62.0. (#1398)

* Bump more ad-hoc versions.

* Add build.rs to wasi-common's Cargo.toml.

* Update the env var name in more places.

* Remove a redundant echo.

crates/fuzzing/Cargo.toml

@@ -4,7 +4,7 @@ description = "Fuzzing infrastructure for Wasmtime"
 edition = "2018"
 name = "wasmtime-fuzzing"
 publish = false
-version = "0.14.0"
+version = "0.15.0"
 
 [dependencies]
 anyhow = "1.0.22"
@@ -15,7 +15,7 @@ log = "0.4.8"
 rayon = "1.2.1"
 wasmparser = "0.51.2"
 wasmprinter = "0.2.1"
-wasmtime = { path = "../api", version = "0.14.0" }
+wasmtime = { path = "../api", version = "0.15.0" }
 
 [dev-dependencies]
 wat = "1.0.10"