pmix: fix misc memory leaks involving opal_convert_jobid_to_string

[ggouaillardet]

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[ggouaillardet]

@rhc54 i initially prepared this PR in order to fix misc memory leaks
opal_convert_jobid_to_string allocates the result via asprintf but it is never released.

then i found that except in _cnt from orte/orted/pmix/pmix_server_dyn.c, we only use the result of this function as a parameter of snprintf.
bottom line, and though this is clearly not in the critical path, that is pretty unefficient and require extra code to free the allocated memory.

wouldn't it be better to replace opal_convert_jobid_to_string with opal_snprintf_jobid
and update _cnt accordingly (e.g. use a char jobid[xxx]; like local variable ) ?

i can make a new PR if you agree this is the way to go

[rhc54]

@ggouaillardet I agree with your alternate approach - there are multiple places in the code base where that would be a better. Problem is to figure out a reasonable max size - right now, for OMPI internals, something like 64 or 128 characters would be fine.

[ggouaillardet]

@rhc54 i did that in #1302
now closing this PR