Fix DESTDIR behavior at install time.

[phcerdan]

We have to read DESTDIR at install time, not at configure time.
so we escape the $ symbol.
\$ENV{DESTDIR}

The same with TABLE_DIR inside configure_file.

Read more: https://cmake.org/pipermail/cmake-developers/2013-January/017810.html

Fix #1229

Checklist

• [NA] Unit-test of your feature with Catch.
• [NA] Doxygen documentation of the code completed (classes, methods, types, members...)
• [NA] Documentation module page added or updated.
• New entry in the ChangeLog.md added.
• No warning raised in Debug cmake mode (otherwise, Travis C.I. will fail).
• All continuous integration tests pass (Travis & appveyor)

[copyme]

@phcerdan It is pity that this is not documented in CMake. I already mentioned about doc problems and DESTDIR via issue tracker of CMake. I hope it is going to be improved soon.

[phcerdan]

@copyme yeah, they should document that install(CODE... and install(SCRIPT... don't manage DESTDIR by themselves. Thanks for that.
The tricky part here is that cmake generates a cmake_install.cmake at configure time, that will control the future installation. If we just put $ENV{DESTIR} it will be transformed to a string literal in cmake_install.cmake with the value at configure time of DESTIR (usually empty). But if we want cmake_install.cmake to read at install time $ENV{DESTIR}, it should be escaped.

I am not sure how well documented the escaping behavior is. But use of cpack requires two escape layers, (so for cpack to read \ it needs \\\), install(CODE...) requires one, etc...

[copyme]

@phcerdan I came to a conclusion that it would be better to start a new issue. See https://gitlab.kitware.com/cmake/cmake/issues/16583

[phcerdan]

@copyme commented there as well.

[copyme]

@phcerdan I saw your comment. Thanks for the additional information!

[dcoeurjo]

Hi @phcerdan & @copyme,
We're preparing a DGtal release and this PR is the last one that could be included. Have you found a solution for the @copyme's packing scripts on linux ?
Can I review this PR ?

[copyme]

@dcoeurjo I will make tests on build.opensuse.org, stay tuned ;-)

[phcerdan]

Hey @dcoeurjo definitely. This PR (of one character \) should fix current problem reading DESTDIR at install time. But @copyme tests might ensure that (thanks!)

[copyme]

@dcoeurjo @phcerdan I give you green light guys :-)

[dcoeurjo]

Excellent ! ;)

@phcerdan, could you please add an tiny entry to the changelog (bug fix section) ?

The main drawback is that the commit size would drastically increased ;)

[dcoeurjo]

changelog entry

[phcerdan]

done (rebased)

[dcoeurjo]

👏