CI: remove Travis CI configuration on stable branches

Set secret github token, for auto doc update.

Merge stable-1.8 into stable-1.9

Merge stable-1.7 into stable-1.8

Merge stable-1.6 into stable-1.7

[stable-1.9] docker: fix all images

- fix missing dependencies,
- fix images' FROM path,
- bump dependencies' versions to omit known issues.

tests: add libunwind suppresion

Memcheck reports an error in libunwind exception raising.

[stable-1.6] Ubsan fixes

Origianl implementation resulted in the following array_iterator_noconv_0_test
failure under UBSAN:

"runtime error: applying non-zero offset 4 to null pointer"

[stable-1.8] Ubsan fixes

This fixes following tests under UBSAN:
vector_modifiers_type_requirements_0_none
vector_parameters_0_none

They failed with following error message:

"runtime error: reference binding to null pointer of type"

This fix is continuation of 41ddc88a

Casting unaligned ptr_offset_magic address to pointers is undefined
behavior for types which require alignemnt > 1. It results in following
error under UBSAN for ptr_0_none test:

"runtime error: upcast of misaligned address 0x0000deadbeef for type 'C',
which requires 8 byte alignment"

Also, add test for offset calculation for objects with different
alignment requirements.

On tests listed bellow the reserve method is being called before any
allocation on the object therefore realloc being called without
any previous allocation. Inside realloc _data is being used with the
operator '[]', as it is nullptr at that moment it's an undefined
behaviour.

This patch simply returns a call to alloc if _data is nullptr.

This tests fails on PowerPC with Segmentation Fault because of this
issue:
segment_vector_array_expsize_assign_exceptions_oom_0_none
segment_vector_array_expsize_assign_exceptions_oom_0_memcheck
segment_vector_array_expsize_capacity_exceptions_oom_0_none
segment_vector_array_expsize_capacity_exceptions_oom_0_memcheck
segment_vector_array_expsize_modifiers_exceptions_oom_0_none
segment_vector_array_expsize_modifiers_exceptions_oom_0_memcheck
segment_vector_vector_expsize_assign_exceptions_oom_0_none
segment_vector_vector_expsize_assign_exceptions_oom_0_memcheck
segment_vector_vector_expsize_capacity_exceptions_oom_0_none
segment_vector_vector_expsize_capacity_exceptions_oom_0_memcheck
segment_vector_vector_expsize_modifiers_exceptions_oom_0_none
segment_vector_vector_expsize_modifiers_exceptions_oom_0_memcheck
segment_vector_vector_fixedsize_assign_exceptions_oom_0_none
segment_vector_vector_fixedsize_assign_exceptions_oom_0_memcheck

Signed-off-by: Lucas A. M. Magalhães <lamm@linux.ibm.com>

Merge back stable-1.5 to stable-1.6

CI: use special environment var in GHA for Windows' PATH

The old 'addPath' is depreciated now. For more details see:
https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/

add "rebuild" param to utils' script, to force dockers rebuilding

it makes more sense to rebuild dockers all the time on stable branches,
because we don't have to count on DockerHub's policy to keep our
docker images on their servers.

tests: fix parallel_exec_with sync implementation

Since std::condition_variable::wait can wakeup spuriosly we need to
pass a predicate to wait.

Merge stable-1.8 into stable-1.9