d: Merge upstream dmd, druntime 643b1261bb, phobos 1c98326e7

D front-end changes:

    - Suggested preview switches now give gdc flags (PR109681).
    - `new S[10]' is now lowered to `_d_newarrayT!S(10)'.

D runtime changes:

    - Runtime compiler library functions `_d_newarrayU', `_d_newarrayT',
      `_d_newarrayiT' have been converted to templates.

Phobos changes:

    - Add new `std.traits.Unshared' template.

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 643b1261bb.
	* d-attribs.cc (build_attributes): Update for new front-end interface.
	* d-lang.cc (d_post_options): Likewise.
	* decl.cc (layout_class_initializer): Likewise.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime 643b1261bb.
	* libdruntime/Makefile.am (DRUNTIME_DSOURCES_FREEBSD): Add
	core/sys/freebsd/ifaddrs.d, core/sys/freebsd/net/if_dl.d,
	core/sys/freebsd/sys/socket.d, core/sys/freebsd/sys/types.d.
	(DRUNTIME_DSOURCES_LINUX): Add core/sys/linux/linux/if_arp.d,
	core/sys/linux/linux/if_packet.d.
	* libdruntime/Makefile.in: Regenerate.
	* src/MERGE: Merge upstream phobos 1c98326e7.