[lld] Fix warning in lld/Macho while building lld for wasm (PR #120889)

[Anutosh Bhat via llvm-commits]

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@@ -2084,7 +2084,7 @@ void ObjCMethListSection::writeTo(uint8_t *bufStart) const {
     uint32_t writtenSize = writeRelativeMethodList(isec, buf);
     buf += writtenSize;
   }
-  assert(buf - bufStart == sectionSize &&
+  assert(buf - bufStart == long(sectionSize) &&
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anutosh491 wrote:

Thanks for the review @carlocab 
I have applied the above suggestion. It does make sense to use it in place of `long`

https://github.com/llvm/llvm-project/pull/120889