Fix wrong condition

Author: Oliver Old

backward.hpp

@@ -3637,11 +3637,11 @@ template <> class TraceResolverImpl<system_tag::windows_tag>
       char* lpMsgBuf;
       DWORD dw = GetLastError();
 
-      if (!FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
-                              FORMAT_MESSAGE_FROM_SYSTEM |
-                              FORMAT_MESSAGE_IGNORE_INSERTS,
-                          NULL, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                          (char*)&lpMsgBuf, 0, NULL)) {
+      if (FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                             FORMAT_MESSAGE_FROM_SYSTEM |
+                             FORMAT_MESSAGE_IGNORE_INSERTS,
+                         NULL, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                         (char*)&lpMsgBuf, 0, NULL)) {
       std::fprintf(stderr, "%s\n", lpMsgBuf);
       LocalFree(lpMsgBuf);
     }