Be resilient with Bazel-built transitive dependencies duplicates
- it is possible that some duplicate libraries, built with Bazel, will be passed as inputs to cmake_external or configure_make. rules_foreign_cc should filter duplicates out rather then fail.
- add a test (which just builds the target) //cmake_synthetic:lib_with_duplicate_transitive_bazel_deps
Fix #232 - enable usage of Bazel-built libraries as dependencies of cmake_external and configure_make.
- fix logic of reading library data described by C/C++ Bazel interface (as CcInfo.linking_context appeared)
- symlink transitive include directories under $EXT_BUILD_DEPS
- gather all possible transitive include directories to pass to CMake, pass transitive include directories to CMAKE_PREFIX_PATH so that the transitive include directories were scanned by CMake
- fix logic of passing transitive libraries into CPPFLAGS (configure_make)
- add test with the chain: Bazel lib -> CMake lib -> Bazel cc_test
- add synthetic configure-make test with the chain: Bazel lib -> configure_make lib -> Bazel cc_test
- also notice, that passed include directories from Bazel C/C++ Sandwich interface are not always existing; for now, make symlinking code resistant to that
see https://www.gnu.org/software/autoconf/manual/autoconf-2.63/html_node/Preset-Output-Variables.html
* Extract cmake and ninja into a toolchain; provide defaults.
In the workspace-level rule registration function, default toolchain
implementations are registered for all platforms, which are calling
the cmake and ninja just by name, assuming they are preinstalled.
Also, the user can pass the custom toolchains in the initialization
function, they will be registered before the defaults.
* Do not run ninja build test for now without nested workspaces support
* Corrections after merge
* Always build ninja from sources for tests, correct initialization order
* Add example of using prebuilt artefact in the native tools toolchain.
* Review comments, have native_tool_toolchain#target, not label
+ improve documentation
* Correct ninja toolchain label
* Correct documentation in native_tools_toolchain.bzl
* Reorganize examples to be in a separate workspace
This will help to define native tools toolchains for examples
* Remove examples-related part from main WORKSPACE file
* Copy .bazelrc to the examples workspace.
* correction for Bazel HEAD compatibility
* Changes to run nested workspace tests from main workspace
