GHS: Add toolset selection support

-- Use the specified toolset located within GHS_TOOLSET_ROOT
-- Update how the latest toolset is determined; scan the location GHS_TOOLSET_ROOT and sort it
   No longer use registry settings looking for installations
     The registry values are assigned in installation order for Green Hills tools not version order
-- Update to use gbuild.exe from the proper toolset
-- Clarify that CMAKE_MAKE_PROGRAM should not be set by user.
-- Detect some toolset changes when regenerating project files
   This could occur if GHS_TOOLSET_ROOT was changed by user after the initial project generation
   This could occur if CMAKE_MAKE_PROGRAM was changed at the command line
-- Use placeholder values for CMAKE_<LANG>_COMPILER
   The MULTI build system only uses gbuild to build a project
     gbuild uses the project file to determine which set of compilers to use based on target platform and architecture
     because compiler detection is skipped, placeholder values are used so that CMake does not complain

1 files changed, 5 insertions, 3 deletions

diff --git a/Help/variable/CMAKE_MAKE_PROGRAM.rst b/Help/variable/CMAKE_MAKE_PROGRAM.rst
index a3b997a..4f5a50f 100644
--- a/Help/variable/CMAKE_MAKE_PROGRAM.rst
+++ b/Help/variable/CMAKE_MAKE_PROGRAM.rst
@@ -55,9 +55,11 @@ to configure the project:
   the CMake cache then CMake will use the specified value if
   possible.
 
-* The :generator:`Green Hills MULTI` generator sets this to ``gbuild``.
-  If a user or project explicitly adds ``CMAKE_MAKE_PROGRAM`` to
-  the CMake cache then CMake will use the specified value.
+* The :generator:`Green Hills MULTI` generator sets this to the full
+  path to ``gbuild.exe`` based upon the toolset being used.
+
+  Once the generator has initialized a particular value for this
+  variable, changing the value has undefined behavior.
 
 The ``CMAKE_MAKE_PROGRAM`` variable is set for use by project code.
 The value is also used by the :manual:`cmake(1)` ``--build`` and