swift234

[swiftc] Add test case for crash triggered in swift::TypeChecker::checkConformance(swift::NormalProtocolConformance*)

Stack trace:

```
swift: /path/to/swift/lib/Sema/CSApply.cpp:147: swift::Type swift::constraints::Solution::computeSubstitutions(swift::Type, swift::DeclContext *, swift::Type, swift::constraints::ConstraintLocator *, SmallVectorImpl<swift::Substitution> &) const: Assertion `(conforms || firstArchetype->getIsRecursive() || isOpenedAnyObject(replacement) || replacement->is<GenericTypeParamType>()) && "Constraint system missed a conformance?"' failed.
13 swift           0x0000000000e89f3d swift::TypeChecker::checkConformance(swift::NormalProtocolConformance*) + 2237
17 swift           0x0000000000e47556 swift::TypeChecker::typeCheckDecl(swift::Decl*, bool) + 150
20 swift           0x0000000000ea6d8a swift::TypeChecker::typeCheckClosureBody(swift::ClosureExpr*) + 218
21 swift           0x0000000000ed28bc swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::Expr*, swift::Type, bool, bool, bool) + 812
22 swift           0x0000000000e3548a swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*) + 746
25 swift           0x0000000000ea5ead swift::TypeChecker::typeCheckConstructorBodyUntil(swift::ConstructorDecl*, swift::SourceLoc) + 845
26 swift           0x0000000000ea58b2 swift::TypeChecker::typeCheckAbstractFunctionBodyUntil(swift::AbstractFunctionDecl*, swift::SourceLoc) + 34
27 swift           0x0000000000ea6458 swift::TypeChecker::typeCheckAbstractFunctionBody(swift::AbstractFunctionDecl*) + 136
29 swift           0x0000000000e6a9f4 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int) + 1300
30 swift           0x0000000000cbcedf swift::CompilerInstance::performSema() + 3087
32 swift           0x000000000078b6ff frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2495
33 swift           0x00000000007861c5 main + 2837
Stack dump:
0.	Program arguments: /path/to/swift/bin/swift -frontend -c -primary-file validation-test/compiler_crashers/28267-swift-typechecker-checkconformance.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/28267-swift-typechecker-checkconformance-1f2757.o
1.	While type-checking 'init' at validation-test/compiler_crashers/28267-swift-typechecker-checkconformance.swift:10:27
2.	While type-checking expression at [validation-test/compiler_crashers/28267-swift-typechecker-checkconformance.swift:10:34 - line:10:44] RangeText="{enum S<h{c"
3.	While type-checking 'S' at validation-test/compiler_crashers/28267-swift-typechecker-checkconformance.swift:10:35
<unknown>:0: error: unable to execute command: Aborted
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)
```