Fix minor bugs in TestExprs and TestAliases to fix buildbot breakage
- 'run' alias no longer includes the '--' for positional arguments... does not seem like a real bug.
- 2.234f is not a great number for the float tests (due to precision/printing issues) so use 0.5f instead



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@190100 91177308-0d34-0410-b5e6-96231b3b80d8