Don't pass -O0 to clang_cc1, it is the default.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189910 91177308-0d34-0410-b5e6-96231b3b80d8
Clear LookupResult object if invalid candidate is found.
If source code is invalid, error recovery can lead to name lookup in a set containing invalid declaration. The lookup is stopped once found such declaration, but LookupResult object could remain in inconsistent state. Its destructor triggered a check, which caused assert violation.
This patch fixes PR16964 and PR12791.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189916 91177308-0d34-0410-b5e6-96231b3b80d8
Use %clang_cc1.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189917 91177308-0d34-0410-b5e6-96231b3b80d8
Disable llvm optimizations, but keep -O1 to test available_externally.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189918 91177308-0d34-0410-b5e6-96231b3b80d8