gcc8 is too old for std::reduce

Index: alc/effects/reverb.cpp
--- alc/effects/reverb.cpp.orig
+++ alc/effects/reverb.cpp
@@ -931,8 +931,8 @@ void EarlyReflections::updateLines(const float density
     /* Calculate the gain (coefficient) for the secondary reflections based on
      * the average delay and decay time.
      */
-    const auto length = std::reduce(EARLY_LINE_LENGTHS.begin(), EARLY_LINE_LENGTHS.end(), 0.0f)
-        / float{EARLY_LINE_LENGTHS.size()} * density_mult;
+    const auto length = std::accumulate(EARLY_LINE_LENGTHS.begin(), EARLY_LINE_LENGTHS.end(), 0.0f)
+        / static_cast<float>(EARLY_LINE_LENGTHS.size()) * density_mult;
     Coeff = CalcDecayCoeff(length, decayTime);
 
 }
