Fix failure of test suite on POSIX ...

failure due to change of escaping of posix paths in phobos

Also add options when we combine buildsettings (#2363) ...

* Also add options when we combine buildsettings

* include all the buildsettings in add(bs)

Co-authored-by: WebFreak001 <gh@webfreak.org>

Testsuite: Fix calls to die to always include line numbers ...

'die' actually taking two parameters seems to be a little-known fact.

Revert "enable feature by default for testing" ...

This reverts commit 25e0387.

- also explicity add flag for dub describe test

test cases for version filters ...

- tests all combinations of inferred, specified, and inherited version filters

rewrite generator targets configuration ...

- as discusses in in https://github.com/dlang/dub/pull/1128 change the
  configuration algorithm to solve polluting sibling dependencies with
  compiler flags (e.g. versions), thus making it possible to better
  reuse cached builds

0. collect dependencies and shallow configuration
1. downwards inherit versions, debugVersions, and inheritable build options
2. define Have_dependency_xyz for all direct dependencies
3. upwards inherit dflags, versions, debugVersions, import paths,
    string import paths (and libs, lflags for static libs)
4. override string import files in dependencies

unify flags and error handling ...

- also add trap ERR handler to report exact error location

fix OSX test ...

- libcrypto has an additional dependency on libz
- use non-existent libraries to avoid any pkg-config differences

don't use hardcoded dmd

mktemp on OSX requires a template

Fix #624: --data=libs should output in compiler-format, not linker format.

Fixed: --data=linker-files misses linker files specified in dub.json.

Change order of describe-data tests, list should run before dmd as it's easier to debug.