lib: add libc and micro libc

lib/ulibc/unistd/sbrk.c

@@ -0,0 +1,25 @@
+#include <mango/types.h>
+#include <mango/vm.h>
+#include <stdint.h>
+
+#define BRK_SIZE 0x400000
+
+static kern_handle_t heap_region = KERN_HANDLE_INVALID;
+static kern_handle_t heap_object = KERN_HANDLE_INVALID;
+
+static void *init_brk(size_t size)
+{
+	kern_status_t status = KERN_OK;
+	return NULL;
+}
+
+void *sbrk(intptr_t increment)
+{
+	kern_status_t status = KERN_OK;
+	if (heap_region == KERN_HANDLE_INVALID
+	    || heap_object == KERN_HANDLE_INVALID) {
+		return init_brk(BRK_SIZE);
+	}
+
+	return (void *)-1;
+}