resolve configure issue, include stdint, and resolve illegal instruction crash

[vamsiDT]

Hi,

I had several issues with compilation. I resolved them as follows:

1. There is an error during ns3 configure due to cmakelists in src/applications. This error should now be resolved (in conjunction with the pull request on the main repository)
2. There were errors regarding undefined uint8_t and including stdint should resolve it
3. Missing return statement caused crashes especially when using multiple threads, gdb revealed the exact line that was causing this issue. Just added return 0 to a function in rdma-hw.cc

[zhiyuanlv]

I met exactly the same issues of 2 and 3 on Ubuntu 24.04. They are related to gcc version v14 as v13 in Ubuntu 22.04 seems OK: the header file was implicitly included from other header files, and g++ v13 won't generate ud2 for the missing-return case.

Please the maintainer merge this pull request to save others debugging efforts while trying the project. Thanks!