warning C4310: cast truncates constant value

Change-Id: Id5535ec71c47ad29283607d1d1b9f3a502e34fe1

filter/source/svg/svgfilter.cxx

@@ -270,7 +270,7 @@ bool SVGFilter::isStreamGZip(uno::Reference<io::XInputStream> xInput)
     if (nBytes == 2)
     {
         const sal_Int8* pBuffer = aBuffer.getConstArray();
-        if (pBuffer[0] == (sal_Int8)0x1F && pBuffer[1] == (sal_Int8)0x8B)
+        if (pBuffer[0] == 0x1F && static_cast<sal_uInt8>(pBuffer[1]) == 0x8B)
             return true;
     }
     return false;