[libc] Add new libc

This new libc is mostly from scratch, with *printf() functions provided
by Marco Paland and Eyal Rozenberg's tiny printf library, and malloc and
friends provided by dlmalloc.

src/libraries/libc/stdio/putchar.cpp

@@ -0,0 +1,3 @@
+#include <stdio.h>
+
+int putchar(char c) {return 0;}