Do this by tracking CMAKE_CURRENT_{SOURCE,BINARY}_DIR variables.
This is achieved by injecting CMake code with CMAKE_PROJECT_INCLUDE
and overriding some builtin functions with a wrapper that adds
additional trace information.
* xenial doesn't ship many dependencies, so make them all optional
since we don't guarantee that everything will work
* cmake/{5,6}: needs stdlib.h for EXIT_SUCCESS on GCC 5
* common/222: needs C++11, and GCC 5 doesn't understand `auto`
correctly unless we explicitly enable it.
* frameworks/1 boost: xenial doesn't ship boost_python3, so make it
properly optional
* frameworks/6 gettext: gettext can be installed without xgettext,
which doesn't cause the project to fail, but the installed files
list is different which causes the test to fail.
* frameworks/7 gnome: gobject-introspection can't be enabled because
the sanitizer unit test detects leaks in glib and fails
This fixes an issue with generated sources and object libraries, as
well as an issue on windows with the `link` linker and the vs backend.
The last issue is resolved by building the source files multiple times
to avoid extracting object files in meson.
cmake: get language from Meson project if not specified as depedency(..., langugage: ...)
deps: add threads method:cmake
dependency('threads', method: 'cmake') is useful for cmake unit tests
or those who just want to find threads using cmake.
cmake: project(... Fortran) generally also requires C language
This PR refactors the old output_target_map, which was a
raw dict, into it's own class. This makes the access to
the map more uniform and robust (at the cost of more lines
of code).
Additionally relative paths to the build directory are
now also tracked for outputs. This is neccessary to
corretcly distingluish files with the same name, that are
in different directories.