[readme] fix wrong argument for make

Arguments starting from '-D' are typically CMake options.

cmake: replace, not add Ob flag in WIN32

without this change we got build warning (D9025).
With this change comes a small refactor of the 'add_flag' macro,
to allow easily add 'replace_flag' macro.

Add example for usage cmap with pmem string

gha: change IMG_VER from latest to tag version on release

Extend CMake prints

cmake: add /Zc:__cplusplus only on windows

ref: https://bugzilla.redhat.com/show_bug.cgi?id=1923435

and remove redundant check - default value is set to current bin dir.

at least on Debian, it's not allowed to set sha as a package version.

Part of #989

Add ChangeLog 1.12-rc1

doc: change maintainer contact info

and for stables, use version from the branch name

Fix examples tests

transaction: remove unnecessary return

print message only if needed and check whitespace in all tests' common files.

without it will fail. SRC_DIR is set (in cmake) for each test based on test name.

CI: fix var name in build.sh and remove redundant WORKDIR var in gha.yml

Reported by coverity

and minor updates in run-build.sh

Fix doxygen docs

CI: minor fixes in CI and utils scripts

and use them in run-*.sh scripts.

- add missing TIMEOUT setup in other_OSes.yml,
- remove redundant code,
- cleanup comments and vars,
- use github.workspace var to set host workdir,
- get rid of old travis gitignore entry.

example: add radix_tree example with complex value type