kernel/main: Fix implicit declaration of function warnings

kernel/main.c: In function 'bootstrap2':
kernel/main.c:138:9: warning: implicit declaration of function 'bio_init' [-Wimplicit-function-declaration]
  138 |         bio_init();
      |         ^~~~~~~~
kernel/main.c:141:9: warning: implicit declaration of function 'fs_init' [-Wimplicit-function-declaration]
  141 |         fs_init();
      |         ^~~~~~~

kernel/main.c

@@ -35,6 +35,13 @@
 #include <kernel/dpc.h>
 #include <boot_stats.h>
 
+#if WITH_LIB_BIO
+#include <lib/bio.h>
+#endif
+#if WITH_LIB_FS
+#include <lib/fs.h>
+#endif
+
 extern void *__ctor_list;
 extern void *__ctor_end;
 extern int __bss_start;