Add #include "swift/Basic/Assertions.h" to a lot of source files

Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)

lib/Frontend/ModuleInterfaceBuilder.cpp

@@ -19,6 +19,7 @@
 #include "swift/AST/DiagnosticsSema.h"
 #include "swift/AST/FileSystem.h"
 #include "swift/AST/Module.h"
+#include "swift/Basic/Assertions.h"
 #include "swift/Basic/Defer.h"
 #include "swift/Frontend/Frontend.h"
 #include "swift/Frontend/ModuleInterfaceSupport.h"