Fix CQS signal modernize-use-nullptr in xplat/js/react-native-github/packages/react-native/ReactCommon/cxxreact (#51783)

Summary: Pull Request resolved: #51783

Reviewed By: dtolnay

Differential Revision: D75852593

fbshipit-source-id: 410e0693a65a25eeec9bb26292336cee5072b12c

Author: generatedunixname89002005287564

packages/react-native/ReactCommon/cxxreact/JSBigString.cpp

@@ -60,8 +60,8 @@ const char* JSBigFileString::c_str() const {
     return "";
   }
   if (!m_data) {
-    m_data =
-        (const char*)mmap(0, m_size, PROT_READ, MAP_PRIVATE, m_fd, m_mapOff);
+    m_data = (const char*)mmap(
+        nullptr, m_size, PROT_READ, MAP_PRIVATE, m_fd, m_mapOff);
     CHECK(m_data != MAP_FAILED)
         << " fd: " << m_fd << " size: " << m_size << " offset: " << m_mapOff
         << " error: " << std::strerror(errno);