misc: adjust to compiler bug on RedHat 7

RedHat Enterprise Linux 7 has a bug in its toolchain - `std::string`
doesn't have `noexcept` default constructor despite standard demands it.
Unfortunately, this problem is popular and our users have filed several
reports of build failure because of this bug - constructor of `Stream`
cannot be declared as `Stream() noexcept = default;` because it contains
`std::string` fields which cannot be noexcept-default-constructible.
Let's simply replace it with `Stream() noexcept {};` construction - it
won't actually change anything anyway.

Author: drewdzzz

src/Client/Stream.hpp

@@ -121,7 +121,12 @@ struct ConnectOptions {
 class Stream {
 public:
 	/* Disabled copy, enabled move. */
-	Stream() noexcept = default;
+	/*
+	 * Sic: toolchain of RedHat 7 doesn't have `noexcept` qualifier for `std::string`
+	 * default constructor despite standard demands it. That's why `= default` syntax
+	 * wouldn't work there, so let's define default constructor explicitly.
+	 */
+	Stream() noexcept {}
 	~Stream() noexcept = default;
 	Stream(const Stream &) = delete;
 	Stream &operator=(const Stream &) = delete;