It blocked also under-source builds (a subdir inside tree, as suggested
by the documentation), and completely external directories.  On the other
hand, after removing this block, in-source builds work perfectly.

doc: librpma.7: sync and async modes

doc: add parentheses

rpma: write 'MEMORY MANAGEMENT' section of manual

doc: librpma.7: Server Operation

doc: improve librpma.7 formatting

doc: add SEE ALSO section (completion, err, log)

doc: add SEE ALSO section (ep, rpma)

doc: add SEE ALSO section (conn)

rpma: fix formatting of 'Client operation'

doc: librpma.7: Client Operation

doc: add SEE ALSO section mr

doc: add SEE ALSO section utils and peer

rpma: librpma.7: Direct Write to PMem

rpma: fix DEBUGGING AND ERROR HANDLING description

common: threads awareness added to log

'rpma_log_set_threshold()/rpma_log_get_threshold()' is incorrectly
formatted by pandoc to:
'**rpma\_log\_set\_threshold**()/rpma\_log\_get\_threshold()'

rpma: write 'DEBUGGING AND ERROR HANDLING' section of manual

rpma: remove const where related RDMA resources might be modified

const removed from all public API calls if pointers passed
to functions are related to resources that might be modified
e.g.:
- mr as destination RMA operation
- peer where ibv_pd is modified
- connection - almost in all cases

rpma: improve comments

rpma: remove conditions

rpma: remove provider error