Replace #include of c files with build system source selection

[skliper]

Is your feature request related to a problem? Please describe.
#include of a c file is not acceptable flight coding style for some organizations and complicates formal verification processes

Describe the solution you'd like
Source selection should be done via build system

Describe alternatives you've considered
None.

Additional context
None.

Requester Info
Jacob Hageman - NASA/GSFC

[skliper]

Moved from #327

osal/src/os/posix/osfileapi.c

*/
--
81 | #include "../portable/os-impl-posix-io.c"
  | The #include pre-processor directive should only be used to include header files.

*/
88 | #include "../portable/os-impl-posix-files.c"
  | The #include pre-processor directive should only be used to include header files.
89


*/
--
95 | #include "../portable/os-impl-posix-dirs.c"
  | The #include pre-processor directive should only be used to include header files.

posix/osapi.c:

/* use the portable version of OS_ConsoleWrite_Impl() */
--
2411 | #include "../portable/os-impl-console-directwrite.c"
  | The #include pre-processor directive should only be used to include header files.

posix/osloader.c

*/
--
32 | #include "../portable/os-impl-posix-dl.c"
  | The #include pre-processor directive should only be used to include header files.

posix/osnetwork.c

*/
--
58 | #include "../portable/os-impl-bsd-sockets.c"
  | The #include pre-processor directive should only be used to include header files.

posix/osselect.c

/* Leverage the portable UNIX-style Select API for POSIX */
--
35 | #include "../portable/os-impl-bsd-select.c"
  | The #include pre-processor directive should only be used to include header files.

posix/ostimer.c

/* POSIX implements clock_gettime and clock_settime that can be used */
--
566 | #include "../portable/os-impl-posix-gettime.c"
  | The #include pre-processor directive should only be used to include header files.

[jphickey]

A "work in progress" concept is pushed to my osal fork, for review and discussion:

See: https://github.com/jphickey/osal/tree/jph-wip-fix-285-includes

[skliper]

High priority change, submit the pull request on top of other pending merges if you have to.