Correct DOCTEST_NO_INSTALL logic; do install unless it is set

[OdyX]

Description

Commit b63bf85 (fixing #96) introduces the DOCTEST_NO_INSTALL variable, but it's use is reversed: by default it is set to OFF (meaning you do want to install), but the test says "If set to ON, do install".

This made me upload a doctest.h-less doctest-dev package to Debian.

Debian bug

This was detected through a failed build of argagg and reported as https://bugs.debian.org/880721 .

[nm17]

Such a stupid bug I made >.<

[onqtam]

Also my bad for insta-merge of that :)

this will get merged now in master as well without releasing version 1.2.7 - is that ok?

Also many thanks for maintaining a debian package!

[OdyX]

No problem for not releasing 1.2.7; it's patched in Debian already. Thanks for the quick merge!

[a4z]

just also got hit with this, when will 1.2.7 be available?

btw, I do not understand the original issue, adding a no install option. Just do not call make install
I think the whole thing should be removed, useless, just makes the cmake file more complex, and error prone, as proven with this issue

[onqtam]

The fix is currently in master - 1 commit ahead of the 1.2.6 tag. And perhaps a no install option for doctest is necessary when it's used within a bigger cmake project and only other things need to be installed.

about 1.2.7 - perhaps around christmas :)

[a4z]

thanks for your explanation @onqtam
for this case I would suggest thinking about something like

if( ${CMAKE_PROJECT_NAME} STREQUAL ${PROJECT_NAME})
   # have the default install to true, other wise false
endif( ${CMAKE_PROJECT_NAME} STREQUAL ${PROJECT_NAME})

so you can detect if you are included or not and set the proper default per default