[NFC] Swap LLVM_NODISCARD for LLVM_ATTRIBUTE_NORETURN

These were originally meant to be no-return functions since they're going to abort. They were accidentally changed to no-discard functions despite not having a return value.

Author: CodaFi

lib/Demangling/Demangler.cpp

@@ -91,9 +91,10 @@ static bool isRequirement(Node::Kind kind) {
 // Public utility functions    //
 //////////////////////////////////
 
-LLVM_NODISCARD void swift::Demangle::failAssert(const char *file, unsigned line,
-                                                NodePointer node,
-                                                const char *expr) {
+LLVM_ATTRIBUTE_NORETURN void swift::Demangle::failAssert(const char *file,
+                                                         unsigned line,
+                                                         NodePointer node,
+                                                         const char *expr) {
   fprintf(stderr, "%s:%u: assertion failed for Node %p: %s", file, line, node,
           expr);
   abort();

lib/Demangling/DemanglerAssert.h

@@ -51,8 +51,8 @@ namespace swift {
 namespace Demangle {
 SWIFT_BEGIN_INLINE_NAMESPACE
 
-LLVM_NODISCARD void failAssert(const char *file, unsigned line,
-                               NodePointer node, const char *expr);
+LLVM_ATTRIBUTE_NORETURN void failAssert(const char *file, unsigned line,
+                                        NodePointer node, const char *expr);
 
 SWIFT_END_INLINE_NAMESPACE
 } // end namespace Demangle