builtin_macros: expect raw strings too

`expr_to_string` allows raw strings through so this code should be
expected to handle those.

Signed-off-by: David Wood <david@davidtw.co>

compiler/rustc_builtin_macros/src/env.rs

@@ -84,7 +84,7 @@ pub fn expand_env<'cx>(
             // Use the string literal in the code in the diagnostic to avoid confusing diagnostics,
             // e.g. when the literal contains escape sequences.
             let ast::ExprKind::Lit(ast::token::Lit {
-                kind: ast::token::LitKind::Str,
+                kind: ast::token::LitKind::Str | ast::token::LitKind::StrRaw(..),
                 symbol: original_var,
                 ..
             }) = &var_expr.kind

tests/ui/macros/builtin-env-issue-114010.rs

@@ -0,0 +1,6 @@
+// unset-rustc-env:oopsie
+
+env![r#"oopsie"#];
+//~^ ERROR environment variable `oopsie` not defined at compile time
+
+fn main() {}

tests/ui/macros/builtin-env-issue-114010.stderr

@@ -0,0 +1,11 @@
+error: environment variable `oopsie` not defined at compile time
+  --> $DIR/builtin-env-issue-114010.rs:3:1
+   |
+LL | env![r#"oopsie"#];
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = help: use `std::env::var("oopsie")` to read the variable at run time
+   = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+