lib: c: re-organise into separate static modules, plus a single shared library

lib/libc/CMakeLists.txt

@@ -1,4 +1,4 @@
-set(source_dirs core malloc)
+set(source_dirs core malloc io)
 
 set(public_include_dirs
 	${CMAKE_CURRENT_SOURCE_DIR}/include)
@@ -26,5 +26,5 @@ bsp_add_library(
 	NAME libc
 	LIB_DIR /usr/lib)
 
-target_link_libraries(libc libmango)
+target_link_libraries(libc libmango libxpc-static interface::fs)
 target_compile_definitions(libc PRIVATE ENABLE_GLOBAL_HEAP=1)