db/proxy: pass search/find to remote MPD

src/SongFilter.hxx

@@ -61,6 +61,10 @@ public:
 			return tag;
 		}
 
+		bool GetFoldCase() const {
+			return fold_case;
+		}
+
 		const std::string &GetValue() const {
 			return value;
 		}
@@ -105,6 +109,18 @@ public:
 		return items;
 	}
 
+	/**
+	 * Is there at least one item with "fold case" enabled?
+	 */
+	gcc_pure
+	bool HasFoldCase() const {
+		for (const auto &i : items)
+			if (i.GetFoldCase())
+				return true;
+
+		return false;
+	}
+
 	/**
 	 * Returns the "base" specification (if there is one) or an
 	 * empty string.