Merge pull request dotnet/corefx#9121 from ianhays/perfcompression_casing

Fix Compression perf casing error

Commit migrated from https://github.com/dotnet/corefx/commit/401846da0bcefd40e82432f41fa951d0ca5e86f1

src/libraries/System.IO.Compression/tests/Performance/Perf.GZipStream.cs

@@ -74,7 +74,7 @@ public void Compress_Canterbury(int innerIterations, string fileName, Compressio
         [MemberData(nameof(CanterburyCorpus))]
         public void Decompress_Canterbury(int innerIterations, string fileName, CompressionLevel compressLevel)
         {
-            string zipFilePath = Path.Combine("GZTestData", "Canterbury", "GZcompressed", fileName + ".gz");
+            string zipFilePath = Path.Combine("GZTestData", "Canterbury", "GZCompressed", fileName + ".gz");
             string sourceFilePath = Path.Combine("GZTestData", "Canterbury", fileName);
             byte[] outputRead = new byte[new FileInfo(sourceFilePath).Length];
             MemoryStream[] memories = new MemoryStream[innerIterations];