rust: create a cargo workspace

Workspaces allows tracking dependencies for multiple crates at once,
by having a single Cargo.lock file at the top of the rust/ tree.
Because QEMU's Cargo.lock files have to be synchronized with the versions
of crates in subprojects/, using a workspace avoids the need to copy
over the Cargo.lock file when adding a new device (and thus a new crate)
under rust/hw/.

In addition, workspaces let cargo download and build dependencies just
once.  While right now we have one leaf crate (hw/char/pl011), this
will not be the case once more devices are added.

Reviewed-by: Zhao Liu <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

rust/Cargo.toml

@@ -0,0 +1,7 @@
+[workspace]
+resolver = "2"
+members = [
+    "qemu-api-macros",
+    "qemu-api",
+    "hw/char/pl011",
+]

rust/hw/char/pl011/Cargo.toml

@@ -21,6 +21,3 @@ bilge = { version = "0.2.0" }
 bilge-impl = { version = "0.2.0" }
 qemu_api = { path = "../../../qemu-api" }
 qemu_api_macros = { path = "../../../qemu-api-macros" }
-
-# Do not include in any global workspace
-[workspace]

rust/qemu-api-macros/Cargo.toml

@@ -20,6 +20,3 @@ proc-macro = true
 proc-macro2 = "1"
 quote = "1"
 syn = "2"
-
-# Do not include in any global workspace
-[workspace]

rust/qemu-api/Cargo.toml

@@ -20,8 +20,5 @@ qemu_api_macros = { path = "../qemu-api-macros" }
 default = []
 allocator = []
 
-# Do not include in any global workspace
-[workspace]
-
 [lints.rust]
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(MESON)', 'cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)'] }