d: Fix undefined reference to pragma(inline) symbol (PR106563)

Functions that are declared `pragma(inline)' should be treated as if
they are defined in every translation unit they are referenced from,
regardless of visibility protection.  Ensure they always get
DECL_ONE_ONLY linkage, and start emitting them into other modules that
import them.

	PR d/106563

gcc/d/ChangeLog:

	* decl.cc (DeclVisitor::visit (FuncDeclaration *)): Set semanticRun
	before generating its symbol.
	(function_defined_in_root_p): New function.
	(function_needs_inline_definition_p): New function.
	(maybe_build_decl_tree): New function.
	(get_symbol_decl): Call maybe_build_decl_tree before returning symbol.
	(start_function): Use function_defined_in_root_p instead of inline
	test for locally defined symbols.
	(set_linkage_for_decl): Check for inline functions before private or
	protected symbols.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/torture.exp (srcdir): New proc.
	* gdc.dg/torture/imports/pr106563math.d: New test.
	* gdc.dg/torture/imports/pr106563regex.d: New test.
	* gdc.dg/torture/imports/pr106563uni.d: New test.
	* gdc.dg/torture/pr106563.d: New test.