Improve diagnostic on C++11 attribute specifiers that appear at wrong syntactic locations around class specifiers.

This change list implemented logic that explicitly detects several combinations of locations where C++11 attribute
specifiers might be incorrectly placed within a class specifier. Previously we emit generic diagnostics like 
"expected identifier" for such cases; now we emit specific diagnostic against the misplaced attributes, this also 
fixed a bug in old code where attributes appear at legitimate locations were incorrectly rejected.

Thanks to Richard Smith for reviewing!



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168626 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed