Add a libc skeleton with a primitive malloc.

lib/libc/CMakeLists.txt

@@ -0,0 +1,15 @@
+
+add_library(libc STATIC
+  src/malloc.cpp
+  )
+
+target_include_directories(libc
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
+  PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)
+
+target_link_libraries(libc
+  zion_lib
+  )
+
+set_target_properties(libc PROPERTIES
+  COMPILE_FLAGS "${CMAKE_CXX_FLAGS} -ffreestanding -mgeneral-regs-only")