TestClangASTContext: Rewrite an if-else chain into a switch

This avoids the "ambiguous else" warning, which comes from within the
EXPECT_TRUE macro.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@351331 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed