Move the wasmtime crate directories form lib/* to wasmtime-*.

This follows a similar change to Cranelift made here:

https://github.com/CraneStation/cranelift/pull/660

wasmtime-environ/src/lib.rs

@@ -0,0 +1,70 @@
+//! Standalone environment for WebAssembly using Cranelift. Provides functions to translate
+//! `get_global`, `set_global`, `memory.size`, `memory.grow`, `call_indirect` that hardcode in
+//! the translation the base addresses of regions of memory that will hold the globals, tables and
+//! linear memories.
+
+#![deny(missing_docs, trivial_numeric_casts, unused_extern_crates)]
+#![warn(unused_import_braces)]
+#![cfg_attr(feature = "std", deny(unstable_features))]
+#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
+#![cfg_attr(
+    feature = "cargo-clippy",
+    allow(clippy::new_without_default, clippy::new_without_default_derive)
+)]
+#![cfg_attr(
+    feature = "cargo-clippy",
+    warn(
+        clippy::float_arithmetic,
+        clippy::mut_mut,
+        clippy::nonminimal_bool,
+        clippy::option_map_unwrap_or,
+        clippy::option_map_unwrap_or_else,
+        clippy::print_stdout,
+        clippy::unicode_not_nfc,
+        clippy::use_self
+    )
+)]
+#![no_std]
+#![cfg_attr(not(feature = "std"), feature(alloc))]
+
+#[cfg(not(feature = "std"))]
+#[macro_use]
+extern crate alloc as std;
+#[cfg(feature = "std")]
+#[macro_use]
+extern crate std;
+
+#[macro_use]
+extern crate failure_derive;
+
+mod compilation;
+mod func_environ;
+mod module;
+mod module_environ;
+mod tunables;
+mod vmoffsets;
+
+pub mod cranelift;
+
+pub use crate::compilation::{
+    AddressTransforms, Compilation, CompileError, InstructionAddressTransform, Relocation,
+    RelocationTarget, Relocations,
+};
+pub use crate::module::{
+    Export, MemoryPlan, MemoryStyle, Module, TableElements, TablePlan, TableStyle,
+};
+pub use crate::module_environ::{
+    translate_signature, DataInitializer, DataInitializerLocation, FunctionBodyData,
+    ModuleEnvironment, ModuleTranslation,
+};
+pub use crate::tunables::Tunables;
+pub use crate::vmoffsets::{TargetSharedSignatureIndex, VMOffsets};
+
+/// WebAssembly page sizes are defined to be 64KiB.
+pub const WASM_PAGE_SIZE: u32 = 0x10000;
+
+/// The number of pages we can have before we run out of byte index space.
+pub const WASM_MAX_PAGES: u32 = 0x10000;
+
+/// Version number of this crate.
+pub const VERSION: &str = env!("CARGO_PKG_VERSION");