Add core.sys.freebsd.sys.socket. (#15734)

This adds FreeBSD's extensions to the POSIX sys/socket.h.

druntime/mak/COPY

@@ -191,6 +191,7 @@ COPY=\
 	$(IMPDIR)\core\sys\freebsd\sys\link_elf.d \
 	$(IMPDIR)\core\sys\freebsd\sys\mman.d \
 	$(IMPDIR)\core\sys\freebsd\sys\mount.d \
+	$(IMPDIR)\core\sys\freebsd\sys\socket.d \
 	$(IMPDIR)\core\sys\freebsd\sys\sysctl.d \
 	\
 	$(IMPDIR)\core\sys\dragonflybsd\dlfcn.d \

druntime/mak/SRCS

@@ -186,6 +186,7 @@ SRCS=\
 	src\core\sys\freebsd\sys\link_elf.d \
 	src\core\sys\freebsd\sys\mman.d \
 	src\core\sys\freebsd\sys\mount.d \
+	src\core\sys\freebsd\sys\socket.d \
 	src\core\sys\freebsd\sys\sysctl.d \
 	\
 	src\core\sys\dragonflybsd\dlfcn.d \

druntime/src/core/sys/freebsd/sys/socket.d

@@ -0,0 +1,131 @@
+//Written in the D programming language
+
+/++
+    D header file for FreeBSD's extensions to POSIX's sys/socket.h.
+
+    Copyright: Copyright 2023
+    License:   $(HTTP www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
+    Authors:   $(HTTP jmdavisprog.com, Jonathan M Davis)
+ +/
+module core.sys.freebsd.sys.socket;
+
+public import core.sys.posix.sys.socket;
+
+version (FreeBSD):
+extern(C):
+@nogc:
+nothrow:
+
+// Creation flags, OR'ed into socket() and socketpair() type argument.
+enum : uint
+{
+    SOCK_CLOEXEC  = 0x10000000,
+    SOCK_NONBLOCK = 0x20000000,
+}
+
+// Option flags per-socket.
+enum : uint
+{
+    SO_USELOOPBACK  = 0x00000040,
+    SO_TIMESTAMP    = 0x00000400,
+    SO_ACCEPTFILTER = 0x00001000,
+    SO_BINTIME      = 0x00002000,
+
+    SO_NO_OFFLOAD   = 0x00004000,
+    SO_NO_DDP       = 0x00008000,
+    SO_REUSEPORT_LB = 0x00010000,
+    SO_RERROR       = 0x00020000,
+}
+
+
+// Additional options, not kept in so_options.
+enum : uint
+{
+    SO_LABEL           = 0x1009,
+    SO_PEERLABEL       = 0x1010,
+    SO_LISTENQLIMIT    = 0x1011,
+    SO_LISTENQLEN      = 0x1012,
+    SO_LISTENINCQLEN   = 0x1013,
+    SO_SETFIB          = 0x1014,
+    SO_USER_COOKIE     = 0x1015,
+    SO_PROTOCOL        = 0x1016,
+    SO_PROTOTYPE       = SO_PROTOCOL,
+    SO_TS_CLOCK        = 0x1017,
+    SO_MAX_PACING_RATE = 0x1018,
+    SO_DOMAIN          = 0x1019,
+
+    SO_TS_REALTIME_MICRO = 0,
+    SO_TS_BINTIME        = 1,
+    SO_TS_REALTIME       = 2,
+    SO_TS_MONOTONIC      = 3,
+    SO_TS_DEFAULT        = SO_TS_REALTIME_MICRO,
+    SO_TS_CLOCK_MAX      = SO_TS_MONOTONIC,
+}
+
+/+
+   Space reserved for new socket options added by third-party vendors.
+   This range applies to all socket option levels.  New socket options
+   in FreeBSD should always use an option value less than SO_VENDOR.
+ +/
+enum : uint
+{
+    SO_VENDOR = 0x80000000,
+}
+
+struct accept_filter_arg
+{
+    char[16]      af_name;
+    char [256-16] af_arg;
+}
+
+// Address families.
+enum : uint
+{
+    AF_LOCAL = AF_UNIX,
+
+    AF_IMPLINK = 3,
+    AF_PUP     = 4,
+    AF_CHAOS   = 5,
+    AF_NETBIOS = 6,
+    AF_ISO     = 7,
+    AF_OSI     = AF_ISO,
+    AF_ECMA    = 8,
+    AF_DATAKIT = 9,
+    AF_CCITT   = 10,
+    AF_SNA     = 11,
+    AF_DECnet  = 12,
+    AF_DLI     = 13,
+    AF_LAT     = 14,
+    AF_HYLINK  = 15,
+
+    AF_ROUTE       = 17,
+    AF_LINK        = 18,
+    pseudo_AF_XTP  = 19,
+    AF_COIP        = 20,
+    AF_CNT         = 21,
+    pseudo_AF_RTIP = 22,
+
+    AF_SIP        = 24,
+    pseudo_AF_PIP = 25,
+    AF_ISDN       = 26,
+    AF_E164       = AF_ISDN,
+    pseudo_AF_KEY = 27,
+
+    AF_NATM            = 29,
+    AF_ATM             = 30,
+    pseudo_AF_HDRCMPLT = 31,
+    AF_NETGRAPH        = 32,
+    AF_SLOW            = 33,
+    AF_SCLUSTER        = 34,
+    AF_ARP             = 35,
+    AF_BLUETOOTH       = 36,
+    AF_IEEE80211       = 37,
+    AF_NETLINK         = 38,
+
+    AF_INET_SDP = 40,
+
+    AF_INET6_SDP = 42,
+    AF_HYPERV    = 43,
+    AF_DIVERT    = 44,
+    AF_MAX       = 44,
+}