d: Merge upstream dmd a5c86f5b9

d: Merge upstream dmd a5c86f5b9

Adds the following new `__traits' to the D language.

 - isDeprecated: used to detect if a function is deprecated.

 - isDisabled: used to detect if a function is marked with @disable.

 - isFuture: used to detect if a function is marked with @__future.

 - isModule: used to detect if a given symbol represents a module, this
   enhancement also adds support using `is(sym == module)'.

 - isPackage: used to detect if a given symbol represents a package,
   this enhancement also adds support using `is(sym == package)'.

 - child: takes two arguments.  The first must be a symbol or expression
   and the second must be a symbol, such as an alias to a member of the
   first 'parent' argument.  The result is the second 'member' argument
   interpreted with its 'this' context set to 'parent'.  This is the
   inverse of `__traits(parent, member)'.

 - isReturnOnStack: determines if a function's return value is placed on
   the stack, or is returned via registers.

 - isZeroInit: used to detect if a type's default initializer has no
   non-zero bits.

 - getTargetInfo: used to query features of the target being compiled
   for, the back-end can expand this to register any key to handle the
   given argument, however a reliable subset exists which includes
   "cppRuntimeLibrary", "cppStd", "floatAbi", and "objectFormat".

 - getLocation: returns a tuple whose entries correspond to the
   filename, line number, and column number of where the argument was
   declared.

 - hasPostblit: used to detect if a type is a struct with a postblit.

 - isCopyable: used to detect if a type allows copying its value.

 - getVisibility: an alias for the getProtection trait.

Reviewed-on: https://github.com/dlang/dmd/pull/12093

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd a5c86f5b9.
	* d-builtins.cc (d_eval_constant_expression): Handle ADDR_EXPR trees
	created by build_string_literal.
	* d-frontend.cc (retStyle): Remove function.
	* d-target.cc (d_language_target_info): New variable.
	(d_target_info_table): Likewise.
	(Target::_init): Initialize d_target_info_table.
	(Target::isReturnOnStack): New function.
	(d_add_target_info_handlers): Likewise.
	(d_handle_target_cpp_std): Likewise.
	(d_handle_target_cpp_runtime_library): Likewise.
	(Target::getTargetInfo): Likewise.
	* d-target.h (struct d_target_info_spec): New type.
	(d_add_target_info_handlers): Declare.