Introduce new module to create search paths of dynamic strings.

Introduce new module to create search paths of dynamic strings.

Introduce a simple DynamicStringPath module to allow the front end
to create and modify a search path from dynamic strings.

gcc/m2/ChangeLog:

	* Make-lang.in (GM2-COMP-BOOT-DEFS): Add
	DynamicStringPath.def.
	(GM2-COMP-BOOT-MODS): Add DynamicStringPath.mod.
	(GM2-COMP-DEFS): Add DynamicStringPath.def.
	(GM2-COMP-MODS): Add DynamicStringPath.mod.
	($(objdir)/m2/gm2-libs-min/SYSTEM.def): Split path into
	multiple -I components.
	($(objdir)/m2/gm2-libs/SYSTEM.def): Ditto.
	($(objdir)/m2/gm2-libs-coroutines/SYSTEM.def): Ditto.
	* gm2-compiler/M2Options.mod: Import DynamicStringPath.
	(SetSearchPath): Reimplement using DynamicStringPath
	procedures.
	* gm2-compiler/M2Search.def (InitSearchPath): Remove.
	(PrependSearchPath): Remove.
	* gm2-compiler/M2Search.mod (SFIO): Remove import.
	(DynamicStringPath): Add import.
	(Directory): Remove.
	(UserPath): Remove.
	(InitialPath): Remove.
	(InitSearchPath): Remove.
	(PrependSearchPath): Remove.
	(FindSourceFile): Re-implement.
	(FindSourceDefFile): Re-implement.
	(FindSourceModFile): Re-implement.
	* gm2-gcc/init.cc (_M2_DynamicStringPath_init):
	New prototype.
	(init_FrontEndInit): Call _M2_DynamicStringPath_init.
	* tools-src/makeSystem: Allow multiple -I paths.
	* gm2-compiler/DynamicStringPath.def: New file.
	* gm2-compiler/DynamicStringPath.mod: New file.
	* gm2-gcc/m2options.h (M2Options_SetMakeIncludePath): Add
	prototype.
	    Co-Authored by: Iain Sandoe  <iain@sandoe.co.uk>

libgm2/ChangeLog:

	* libm2cor/Makefile.am (SYSTEM.def): Split path into
	multiple -I components.
	* libm2cor/Makefile.in: Rebuild.
	* libm2min/Makefile.am (SYSTEM.def): Split path into
	multiple -I components.
	* libm2min/Makefile.in: Rebuild.
	* libm2iso/Makefile.am (SYSTEM.def): Split path into
	multiple -I components.
	* libm2iso/Makefile.in: Rebuild.
	    Co-Authored by: Iain Sandoe  <iain@sandoe.co.uk>

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>