Implemented runtime files and tests

tests/CMakeLists.txt

@@ -0,0 +1,8 @@
+file(GLOB test_sources ${CMAKE_CURRENT_SOURCE_DIR}/*.c)
+
+foreach (test ${test_sources})
+    get_filename_component(test_name ${test} NAME_WE)
+    add_executable(${test_name} ${test} $<TARGET_OBJECTS:crt>)
+    target_compile_options(${test_name} PRIVATE -ffreestanding -nostdlib -nostdinc)
+    target_link_libraries(${test_name} c)
+endforeach (test)

tests/start.c

@@ -0,0 +1,4 @@
+int main(int argc, char **argv)
+{
+    return 42;
+}