pearsonSpearmanCov: Remove variable shadowing

Author: Geod24

source/dstats/cor.d

@@ -1225,8 +1225,8 @@ private void pearsonSpearmanCov(bool makeNewMatrix, RoR, Matrix)
             break;
         case CorCovType.spearman:
             foreach(row; pool.parallel(normalized)) {
-                auto alloc = newRegionAllocator();
-                auto buf = alloc.uninitializedArray!(double[])(row.length);
+                auto localAlloc = newRegionAllocator();
+                auto buf = localAlloc.uninitializedArray!(double[])(row.length);
                 rank(row, buf);
 
                 // Need to find mean, stdev separately for every row b/c