return value of CFE_SB_ReceiveBuffer stub does not match documentation

[CDKnightNASA]

For the stock stub function, it returns the default (CFE_SUCCESS) return code but sets the message pointer to NULL. The documentation states that it defaults to return the TIMEOUT error. The logic for the stub may want to reflect this.

cFE/fsw/cfe-core/ut-stubs/ut_sb_stubs.c

Line 450 in 56397a3

** CFE_SB_ReceiveBuffer. By default it will return the TIMEOUT error response,

[skliper]

Probably worth making it like the other (new-ish) getters, in that it will report an error if the SB buffer has not been provided already (from the UT buffer). Then can remain as the default success (like the other stubs).

[skliper]

This has become a documentation issue (comments on stub description are incorrect).