[lld][MachO][NFC] Pull out code into helper function.

[Roger]

Summary

This is currently in a separate commit for the ease of review.
In the final commits, this will likely be merged into one diff that
includes the functional changes.

[Roger]

small fix.

[Roger]

Compilation fix.

[Roger]

test passes

[int3]

eh I don't think it's necessary to make your changes this granular even for ease of review. this can def be folded into a larger change

[int3]

clearing my queue

lld/MachO/MapFile.cpp

for (OutputSection *osec : seg->getSections()) {
       if (osec->isHidden())
         continue;
 
       os << format("0x%08llX\t0x%08llX\t%s\t%s\n", osec->addr, osec->getSize(),
                    seg->name.str().c_str(), osec->name.str().c_str());
     }
 
   // Dump table of symbols
-  os << "# Symbols:\n";
+  auto writeSymbols = [&](const std::vector<Defined *> &syms) {
     os << "# Address\t    File  Name\n";
     for (Symbol *sym : syms) {
       os << format("0x%08llX\t[%3u] %s\n", sym->getVA(),
                    readerToFileOrdinal[sym->getFile()], symStr[sym].c_str());
     }
+  };
 
+  os << "# Symbols:\n";
+  writeSymbols(syms);
   // TODO: when we implement -dead_strip, we should dump dead stripped symbols
 }