Set CMAKE_BUILD_PARALLEL_LEVEL earlier (take 2)

not sure why previous release didn't create any artifacts... trying again

Set CMAKE_BUILD_PARALLEL_LEVEL earlier

trivial improvements (#105)

* set CMAKE_BUILD_PARALLEL_LEVEL before configuring
just in case some monster decides to build from within the configuration step (cough cough aws-c-cal/cmake/modules/aws-lc.cmake)

* more natural traversal order

Clang fixup take 2

• Hopefully addresses an issue with clang-3.9 builds

Clang fixes and extensions

• fix clang ci by upgrading to ubuntu18 as a base image
• add references to latest clang releases

fix linux-shared-libs runs

fix linux-shared-lib tests (#103)

* set LD_LIBRARY_PATH so linux tests can find shared-libs
* also allow ctest3 alias

limit parallelism to cpu-count

Use cpu-count for parallel builds (#101)

Specify number of CPUs to use. GCC builds were freezing up when using -j without specifying a limit.

--cmake-extra

--cmake-extra lets you add extra cmake args to every project (#99)

The existing `cmake_args` in the config does not affect the building of upstream dependencies

So add new CLI argument we can use like `--cmake-extra=-DBUILD_SHARED_LIBS=ON` and build everything in the tree with a given flag

s2n/aws-lc fixes, bug fixes

aws-lc/s2n fixes (#100)

* Switched s2n from depending on libcrypto to aws-lc

* Updates to s2n/aws-lc to make them play nice

s2n now depends on aws-lc only

v0.8.3

Switched s2n from depending on libcrypto to aws-lc (#98)

Added aws-lc as an import

Added aws-lc as an import (#97)

* Added aws-lc as an import

* Renamed aws-lc -> awslc.py so it gets loaded