Fix fallout

clippy_lints/src/strings.rs

@@ -1,6 +1,6 @@
 use rustc::lint::in_external_macro;
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Spanned;