add IFDEF to negate the content when NET20 since Func not supported under net20
add IFDEF to negate the content when NET20 since Func not supported under net20

Moily/common-logging,net-commons/common-logging,meixger/common-logging,net-commons/common-logging,ajayanandgit/common-logging,xlgwr/common-logging,tablesmit/common-logging