[lld][MachO] Fix -Wsign-compare warning (NFC)

GCC warning:
```
/llvm-project/lld/MachO/InputFiles.cpp:484:24: warning: comparison of integer expressions of different signedness: ‘int64_t’ {aka ‘long int’} and ‘uint64_t’ {aka ‘long unsigned int’} [-Wsign-compare]
484 |           return value < subsectionEntry.offset;
    |                  ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
```

GitOrigin-RevId: d441dee5c266ca0777d06846971e1b436361f361
diff --git a/MachO/InputFiles.cpp b/MachO/InputFiles.cpp
index e31c506..c4db50f 100644
--- a/MachO/InputFiles.cpp
+++ b/MachO/InputFiles.cpp
@@ -480,7 +480,7 @@
     uint64_t offset = sym.n_value - sec.addr;
 
     auto it = llvm::upper_bound(
-        subsecMap, offset, [](int64_t value, SubsectionEntry subsectionEntry) {
+        subsecMap, offset, [](uint64_t value, SubsectionEntry subsectionEntry) {
           return value < subsectionEntry.offset;
         });
     uint32_t size = it != subsecMap.end()