libclang: change getCursorAttr() to return 'const Attr *'


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173583 91177308-0d34-0410-b5e6-96231b3b80d8
libclang: make getCursorParentDecl() return 'const Decl *'


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173584 91177308-0d34-0410-b5e6-96231b3b80d8
libclang: factor out the frequent pattern static_cast<ASTUnit *>(TU->TUData)
into a getter cxtu::getASTUnit(TU)


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@173585 91177308-0d34-0410-b5e6-96231b3b80d8