Some POSIX headers use undeclared definitions

[X512]

This is hrev57940.

Some POSIX headers cause compile errors when included alone because it use definitions from other headers, but not include it. It cause compile failures of 3rd-party software.

/boot/system/develop/headers/posix/netinet/ip6.h:75:25: error: unknown type name 'u_int32_t'
   75 |                         u_int32_t ip6_un1_flow; /* 20 bits of flow-ID */
      |                         ^~~~~~~~~

/boot/system/develop/headers/posix/arpa/nameser.h:118:9: error: unknown type name 'uint16_t'
  118 |         uint16_t                _id;
      |         ^~~~~~~~