Fix kernel close and select bug

[Yaxuan-w]

Description

Fixes #48

kernel close

The updated fdtable API passing fd entry and count instead of real fd into kernel_close function in RawPOSIX, which will cause the actual requested real fd not being closed. Updated code to fit newest API.

select

The initial error occurred because cases where each fd_set was empty were not handled. In the updated code, uninitialized values are automatically assigned to the corresponding fd_set. Additionally, during in-depth debugging, I found that when processing the return value, the fdtable:: function should receive an nfd associated with the kernel file descriptor (i.e., the maximum kernel file descriptor + 1).

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• socketselect.c
• uds-nb-select.c
• uds-socketselect.c

Checklist:

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been added to a pull request and/or merged in other modules (native-client, lind-glibc, lind-project)

[JustinCappos]

Needs This review box is broken. I can't see if I'm approving, but it should say that I requestchanges.