Removed libtine linking workaround from FindDOOCS. Doocs libraries now are themselves linked correctly against tine.

Automatically adding CMAKE_CXX_STANDARD to all projects is giving too much trouble because different CMAKE versions add different --std=gnu... flags which do not play well the the --std=c++... which we use.

This reverts commit ddb4d575.

This confused git massively

The pkg-config file is missing so we have to search for the library
manually

This is a work-around for libDOOCSapi linking against it but expecting
/export/doocs/lib to be in the linker search path (not using rpath)

May be reverted once/if doocs fixes this

FindDOOCS: extend PKG_CONFIG_PATH by directory set via DOOCS_DIR (if set) and the hardcoded default in /export/doocs/...

Fixes #6317