[lld][MachO] Silence "enumeral and non-enumeral type" warning from gcc
gcc complained with
[1110/1140] Building CXX object tools/lld/MachO/CMakeFiles/lldMachO2.dir/SyntheticSections.cpp.o
../../lld/MachO/SyntheticSections.cpp: In function 'int16_t ordinalForDylibSymbol(const lld::macho::DylibSymbol&)':
../../lld/MachO/SyntheticSections.cpp:287:14: warning: enumeral and non-enumeral type in conditional expression [-Wextra]
286 | return config->namespaceKind == NamespaceKind::flat || dysym.isDynamicLookup()
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
287 | ? MachO::BIND_SPECIAL_DYLIB_FLAT_LOOKUP
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
288 | : dysym.getFile()->ordinal;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~