fix: resolve distributed tests compilation failures by correcting preprocessor guard

- Changed  to  in local.hpp.
  Including hpx_main.hpp in a distributed build causes main() to be macro-replaced
  with hpx_startup::user_main, leading to linkage errors in tests that manually
  define main() but happen to include headers that pull in local.hpp.

Signed-off-by: shivansh023023 <singhshivansh023@gmail.com>

Author: Hackathon User

libs/core/include_local/include/hpx/local.hpp

@@ -23,7 +23,7 @@
 
 #include <hpx/config.hpp>
 
-#if defined(HPX_HAVE_DISTRIBUTED_RUNTIME) && !defined(HPX_NO_MAIN)
+#if !defined(HPX_HAVE_DISTRIBUTED_RUNTIME) && !defined(HPX_NO_MAIN)
 #if __has_include(<hpx/hpx_main.hpp>)
 #include <hpx/hpx_main.hpp>    // hpxinspect:noinclude:hpx/hpx_main.hpp
 #endif