-Werror,-Wunused-but-set-variable (clang-cl 13 trunk)

...since 362a21d3a1 "Use explicit function names
for fooA/fooW WinAPI; prefer fooW"

Change-Id: I391ae19b01625602231fbd890ee79073367cb449
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117834
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

xmlsecurity/source/xmlsec/mscrypt/securityenvironment_mscryptimpl.cxx

@@ -383,10 +383,8 @@ uno::Reference< XCertificate > SecurityEnvironment_MSCryptImpl::getCertificate(
     CERT_INFO certInfo ;
 
     // for correct encoding
-    sal_uInt16 encoding ;
     rtl_Locale *pLocale = nullptr ;
     osl_getProcessLocale( &pLocale ) ;
-    encoding = osl_getTextEncodingFromLocale( pLocale ) ;
 
     //Create cert info from issue and serial
     LPCWSTR pszName = o3tl::toW( issuerName.getStr() );