[rust] BUILD.gn according to latest crates.py

Latest crates.py no longer appends ($host_toolchain) for procedural
macros as it's no longer necessary. Update the previously-generated
BUILD.gn files to match its current behavior.

Change-Id: I0e5fad28a77f76e7f4f3bddfb7119f61ce6cdcfe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3529854
Auto-Submit: Adrian Taylor <adetaylor@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/main@{#981838}
NOKEYCHECK=True
GitOrigin-RevId: 2b5c03711b1c37fca73211e5248c2835312f35ea

Author: adetaylor

autocxx/v0_16/BUILD.gn

@@ -15,9 +15,9 @@ cargo_crate("lib") {
   sources = [ "crate/src/lib.rs" ]
   edition = "2021"
   deps = [
-    "//third_party/rust/aquamarine/v0_1:lib($host_toolchain)",
+    "//third_party/rust/aquamarine/v0_1:lib",
     "//third_party/rust/autocxx_engine/v0_16:lib",
-    "//third_party/rust/autocxx_macro/v0_16:lib($host_toolchain)",
+    "//third_party/rust/autocxx_macro/v0_16:lib",
     "//third_party/rust/cxx/v1:lib",
     "//third_party/rust/moveit/v0_4:lib",
   ]

autocxx_engine/v0_16/BUILD.gn

@@ -19,22 +19,22 @@ cargo_crate("lib") {
   sources = [ "crate/src/lib.rs" ]
   edition = "2021"
   deps = [
-    "//third_party/rust/aquamarine/v0_1:lib($host_toolchain)",
+    "//third_party/rust/aquamarine/v0_1:lib",
     "//third_party/rust/autocxx_bindgen/v0_59:lib",
     "//third_party/rust/autocxx_parser/v0_16:lib",
     "//third_party/rust/cxx/v1:lib",
     "//third_party/rust/cxx_gen/v0_7:lib",
-    "//third_party/rust/indoc/v1:lib($host_toolchain)",
+    "//third_party/rust/indoc/v1:lib",
     "//third_party/rust/itertools/v0_10:lib",
     "//third_party/rust/log/v0_4:lib",
     "//third_party/rust/once_cell/v1:lib",
     "//third_party/rust/proc_macro2/v1:lib",
     "//third_party/rust/quote/v1:lib",
     "//third_party/rust/serde_json/v1:lib",
-    "//third_party/rust/strum_macros/v0_23:lib($host_toolchain)",
+    "//third_party/rust/strum_macros/v0_23:lib",
     "//third_party/rust/syn/v1:lib",
     "//third_party/rust/tempfile/v3:lib",
-    "//third_party/rust/unzip_n/v0_1:lib($host_toolchain)",
+    "//third_party/rust/unzip_n/v0_1:lib",
     "//third_party/rust/version_check/v0_9:lib",
   ]
   features = [

autocxx_parser/v0_16/BUILD.gn

@@ -23,7 +23,7 @@ cargo_crate("lib") {
     "//third_party/rust/proc_macro2/v1:lib",
     "//third_party/rust/quote/v1:lib",
     "//third_party/rust/serde/v1:lib",
-    "//third_party/rust/serde_derive/v1:lib($host_toolchain)",
+    "//third_party/rust/serde_derive/v1:lib",
     "//third_party/rust/syn/v1:lib",
   ]
   features = [

proc_macro_error/v1/BUILD.gn

@@ -20,7 +20,7 @@ cargo_crate("lib") {
   edition = "2018"
   deps = [
     "//third_party/rust/proc_macro2/v1:lib",
-    "//third_party/rust/proc_macro_error_attr/v1:lib($host_toolchain)",
+    "//third_party/rust/proc_macro_error_attr/v1:lib",
     "//third_party/rust/quote/v1:lib",
     "//third_party/rust/syn/v1:lib",
   ]

strum_macros/v0_23/BUILD.gn

@@ -22,7 +22,7 @@ cargo_crate("lib") {
     "//third_party/rust/heck/v0_3:lib",
     "//third_party/rust/proc_macro2/v1:lib",
     "//third_party/rust/quote/v1:lib",
-    "//third_party/rust/rustversion/v1:lib($host_toolchain)",
+    "//third_party/rust/rustversion/v1:lib",
     "//third_party/rust/syn/v1:lib",
   ]
 }