libphobos: Fully enable Darwin/i386 support

libphobos: Fully enable Darwin/i386 support

I recently noticed that libphobos isn't enable by default on 32-bit
Darwin with the target triples determined by config.guess.  E.g. on a
Darwin 15 system the target triple is something like
i386-apple-darwin15.6.0 while configure.tgt only matches
i?86-*-darwin1[2-7].

This patch also allows such minor and micro versions.

Tested on i386-apple-darwin15.6.0.

2025-06-30  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	libphobos:
	* configure.tgt <i?86-*-darwin1[2-7]>: Also consider minor
	versions supported.