Add quote!() example to reserved_prefix lint test.

Author: m-ou-se

src/test/ui/rust-2021/reserved-prefixes-migration.fixed

@@ -26,3 +26,13 @@ fn main() {
     //~^ WARNING prefix `hey` is unknown [reserved_prefix]
     //~| WARNING become a hard error
 }
+
+macro_rules! quote {
+    (# name = # kind # value) => {};
+}
+
+quote! {
+    #name = #kind #value
+    //~^ WARNING prefix `kind` is unknown [reserved_prefix]
+    //~| WARNING become a hard error
+}

src/test/ui/rust-2021/reserved-prefixes-migration.rs

@@ -26,3 +26,13 @@ fn main() {
     //~^ WARNING prefix `hey` is unknown [reserved_prefix]
     //~| WARNING become a hard error
 }
+
+macro_rules! quote {
+    (# name = # kind # value) => {};
+}
+
+quote! {
+    #name = #kind#value
+    //~^ WARNING prefix `kind` is unknown [reserved_prefix]
+    //~| WARNING become a hard error
+}

src/test/ui/rust-2021/reserved-prefixes-migration.stderr

@@ -55,5 +55,18 @@ help: insert whitespace here to avoid this being parsed as a prefix in Rust 2021
 LL |     m3!(hey #hey);
    |            --
 
-warning: 4 warnings emitted
+warning: prefix `kind` is unknown
+  --> $DIR/reserved-prefixes-migration.rs:35:14
+   |
+LL |     #name = #kind#value
+   |              ^^^^ unknown prefix
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2021 edition!
+   = note: for more information, see issue #84978 <https://github.com/rust-lang/rust/issues/84978>
+help: insert whitespace here to avoid this being parsed as a prefix in Rust 2021
+   |
+LL |     #name = #kind #value
+   |                  --
+
+warning: 5 warnings emitted