Fix compilation failure in Utf16Utility

Commit migrated from https://github.com/dotnet/coreclr/commit/7558272c50a01bb043569c312172a2be019fad61

diff --git a/src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs b/src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs
index 4bc2c1c..40e818e 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs
@@ -226,7 +226,7 @@ namespace System.Text.Unicode
                             else
                             {
                                 // Take the hit of the 64-bit extension now.
-                                tempUtf8CodeUnitCountAdjustment -= 2 * surrogatePairsCountNuint;
+                                tempUtf8CodeUnitCountAdjustment -= 2 * (uint)surrogatePairsCountNuint;
                             }
                         }