[test] Add some more known crashers

Author: hamishknight

validation-test/IDE/crashers/GenericSignatureImpl-getReducedType-05f48c.swift

@@ -0,0 +1,7 @@
+// {"kind":"complete","original":"94ef21bb","signature":"swift::GenericSignatureImpl::getReducedType(swift::Type) const"}
+// RUN: not --crash %target-swift-ide-test -code-completion -batch-code-completion -skip-filecheck -code-completion-diagnostics -source-filename %s
+protocol a : b
+protocol c {
+associatedtype d : a#^^# where d.e == f
+}
+struct b<g : c

validation-test/compiler_crashers/DeclContext-getParentModule-a33d74.swift

@@ -0,0 +1,6 @@
+// {"kind":"typecheck","original":"16240db9","signature":"swift::DeclContext::getParentModule() const"}
+// RUN: not --crash %target-swift-frontend -typecheck %s
+@a({
+  unowned protocol b
+  }
+  let c

validation-test/compiler_crashers/RewriteContext-getRequirementMachine-5d36d2.swift

@@ -0,0 +1,9 @@
+// {"kind":"typecheck","original":"0004c325","signature":"swift::rewriting::RewriteContext::getRequirementMachine(swift::ProtocolDecl const*)"}
+// RUN: not --crash %target-swift-frontend -typecheck %s
+protocol a {
+  associatedtype b: a
+  associatedtype c: a
+  where
+    d == Self,
+    c.c.b.c.c.b == Self, b.e == Self
+}