[clang-tidy] remove redundant access specifiers

Found with readability-redundant-access-specifiers

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/output/plugins/OpenALOutputPlugin.cxx

@@ -70,7 +70,6 @@ private:
 
 	void Cancel() noexcept override;
 
-private:
 	[[nodiscard]] gcc_pure
 	ALint GetSourceI(ALenum param) const noexcept {
 		ALint value;