[lld-macho] Fix -Wsuggest-override after D99633. NFC

GitOrigin-RevId: c318746345cc68ecb3c1ac420baa2102e83f716f
diff --git a/MachO/Writer.cpp b/MachO/Writer.cpp
index 01f6d4f..f37322b 100644
--- a/MachO/Writer.cpp
+++ b/MachO/Writer.cpp
@@ -175,12 +175,12 @@
 public:
   LCSegment(StringRef name, OutputSegment *seg) : name(name), seg(seg) {}
 
-  uint32_t getSize() const {
+  uint32_t getSize() const override {
     return sizeof(typename LP::segment_command) +
            seg->numNonHiddenSections() * sizeof(typename LP::section);
   }
 
-  void writeTo(uint8_t *buf) const {
+  void writeTo(uint8_t *buf) const override {
     using SegmentCommand = typename LP::segment_command;
     using Section = typename LP::section;