Fix missing headers, generate compile db with bear

kernel/libk/string.h

@@ -1,6 +1,8 @@
 #ifndef _KERNEL_LIBK_STRING_H
 #define _KERNEL_LIBK_STRING_H
 
+#include <libk/std.h>
+
 size_t memset (void* dst, uint8_t b, size_t n);
 size_t memcpy (void* dst, const void* src, size_t n);
 void strncpy (char* dst, const char* src, size_t n);