d: Add option to include imported modules in the compilation [PR109023]

d: Add option to include imported modules in the compilation [PR109023]

Adds the ability to include imported modules in the compilation, as if
they were given on the command line.  When this option is enabled, all
imported modules are compiled except those that are part of libphobos.

	PR d/109023

gcc/d/ChangeLog:

	* d-compiler.cc: Include dmd/errors.h.
	(Compiler::onImport): Implement.
	* d-lang.cc (d_handle_option): Handle -finclude-imports.
	(d_parse_file): Run semantic on included imports.
	* gdc.texi: Document -finclude-imports.
	* lang.opt: Add finclude-imports.
	* lang.opt.urls: Regenerate.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/imports/pr109023.d: New test.
	* gdc.dg/torture/pr109023.d: New test.