Revert "Delete and re-add libpqxx-7.7.3 due to weird corruption."

This reverts commit e96515433d.

ext/libpqxx-7.7.3/tools/rmlo.cxx

@@ -0,0 +1,39 @@
+// Remove large objects given on the command line from the default database.
+#include <iostream>
+
+#include "pqxx/pqxx"
+
+
+int main(int, char *argv[])
+{
+  pqxx::connection conn;
+  bool failures = false;
+
+  try
+  {
+    for (int i{1}; argv[i]; ++i)
+    {
+      auto o{pqxx::from_string<pqxx::oid>(argv[i])};
+      try
+      {
+        pqxx::perform([o, &conn] {
+          pqxx::work tx{conn};
+          pqxx::blob::remove(tx, o);
+          tx.commit();
+        });
+      }
+      catch (std::exception const &e)
+      {
+        std::cerr << e.what() << std::endl;
+        failures = true;
+      }
+    }
+  }
+  catch (std::exception const &e)
+  {
+    std::cerr << e.what() << std::endl;
+    return 2;
+  }
+
+  return failures;
+}