VS2015: remove previously ignored C4146 in kiss_fft.c

C4146: unary minus operator applied to unsigned type, result still unsigned

Fixed in a previous commit.

Signed-off-by: Mark Harris <mark.hsj@gmail.com>

win32/VS2015/opus.vcxproj

@@ -248,9 +248,7 @@
     <ClCompile Include="..\..\celt\entcode.c" />
     <ClCompile Include="..\..\celt\entdec.c" />
     <ClCompile Include="..\..\celt\entenc.c" />
-    <ClCompile Include="..\..\celt\kiss_fft.c">
-      <DisableSpecificWarnings Condition="'$(Configuration)'=='DebugDLL_fixed'">4146;%(DisableSpecificWarnings)</DisableSpecificWarnings>
-    </ClCompile>
+    <ClCompile Include="..\..\celt\kiss_fft.c" />
     <ClCompile Include="..\..\celt\laplace.c" />
     <ClCompile Include="..\..\celt\mathops.c" />
     <ClCompile Include="..\..\celt\mdct.c" />