[Docs] Rewrite build documentation (#510)

* Rewrites build documentation
  * Splits documentation into several files
* Adds docs for using with CMake.

Author: hjabird

docs/building_and_running_tests.rst

@@ -0,0 +1,39 @@
+.. _building_and_running_tests:
+
+Building and Running Tests
+==========================
+
+The functional tests are enabled by default, and can be enabled/disabled
+with the CMake build parameter ``-DBUILD_FUNCTIONAL_TESTS=True/False``. Only
+the tests relevant to the enabled backends and target domains will be built.
+
+Building tests for BLAS and LAPACK domains requires additional libraries for
+reference.
+
+* BLAS: Requires a reference BLAS library.
+* LAPACK: Requires a reference LAPACK library.
+
+For both BLAS and LAPACK, shared libraries supporting both 32 and 64 bit
+indexing are required.
+
+A reference LAPACK implementation (including BLAS) can be built as the
+following:
+
+.. code-block:: bash
+
+  git clone https://github.com/Reference-LAPACK/lapack.git 
+  cd lapack; mkdir -p build; cd build 
+  cmake -DCMAKE_INSTALL_PREFIX=~/lapack -DCBLAS=True -DLAPACK=True -DLAPACKE=True -DBUILD_INDEX64=True -DBUILD_SHARED_LIBS=True .. 
+  cmake --build . -j --target install 
+  cmake -DCMAKE_INSTALL_PREFIX=~/lapack -DCBLAS=True -DLAPACK=True -DLAPACKE=True -DBUILD_INDEX64=False -DBUILD_SHARED_LIBS=True .. 
+  cmake --build . -j --target install
+
+and then used in oneMKL by setting ``-REF_BLAS_ROOT=/path/to/lapack/install``
+and ``-DREF_LAPACK_ROOT=/path/to/lapack/install``.
+
+To run the tests, either use the CMake test driver, by running ``ctest``, or run
+individual test binaries individually.
+
+When running tests you may encounter the issue ``BACKEND NOT FOUND EXCEPTION``,
+you may need to add your ``<oneMKL build directory>/lib`` to your
+``LD_LIBRARY_PATH`` on Linux.