MM IntLock removed, no longer implements "write with interrupts disabled" requirement MM2003

Historical - (note the lock/unlock have been removed, see comments):
Memory Manager uses OS_IntLock() and OS_IntUnlock(). That's the only place any of the OS_Int* functions are used in the GSFC apps. These functions will likely be deprecated in the next OSAL release.

I'm guessing it does this with the intent of loading the mem block "atomically" with the hope of preventing another task from writing to it while this happens?

IntLock/Unlock has always been a no-op on POSIX, and furthermore even on platforms where it does something, it will not achieve that exclusivity effect on Multi-Core CPUs, as it only locks the interrupts on the core which calls it, and other cores continue to run anyway, interrupt or not.

Probably worth re-evaulating what MM is trying to achieve with the intlock... might be able to simply take it out with no loss of function.

20220324 - OS_IntLoc and OS_IntUnlock were removed as part of GSFCCFS-1156. Although now requirement GSFCCFS-611 isn't being met.

Imported from GSFCCFS-1132

Start by reviewing the MM memory-block loading path and the history around GSFCCFS-1156, then compare the current behavior with requirement GSFCCFS-611. Done means determining how the write-with-interrupts-disabled requirement should be satisfied on multicore systems, or documenting and resolving why that requirement no longer applies.