[m-rev.] for review: updates for Boehm GC build system

[Julien Fischer]

For review by Peter.

With the diff below, Mercury now bootstraps with the 64-bit version of 
MSVC in hlc.gc.  (There are a handful of test failures due to "Windows 
things", but it otherwise works.)

I'm not sure what the procedure is for making changes to our local 
modifications to the Boehm collector -- there is a document in
compiler/notes but it is about updating the gc as a whole.

Julien.

----------------------------------

Updates for Boehm GC build system.

Mmakefile:
     Build the 64-bit version of the collector when building MSVC.

     Delete references to the mps garbage collector.

Makefile.direct:
     Do not pass the deprecated --no-ansi option to the mnguc script.

diff --git a/Makefile.direct b/Makefile.direct
index f82fe2c..ac43aa3 100644
--- a/Makefile.direct
+++ b/Makefile.direct
@@ -51,7 +51,7 @@ AS_ABI_FLAG=$(ABI_FLAG)
  # CC=cc $(ABI_FLAG)

  # Mercury-specific definition of CC.
-CC=$(MERCURY_DIR)/scripts/mgnuc --grade $(GRADE) --no-ansi --no-check --no-mercury-stdlib-dir
+CC=$(MERCURY_DIR)/scripts/mgnuc --grade $(GRADE) --no-check --no-mercury-stdlib-dir

  CXX=g++ $(ABI_FLAG)
  # Needed only for "make c++", which adds the c++ interface.
diff --git a/Mmakefile b/Mmakefile
index 7faeac3..24e4fa1 100644
--- a/Mmakefile
+++ b/Mmakefile
@@ -1,5 +1,6 @@
  #-----------------------------------------------------------------------------#
  # Copyright (C) 1995-2004, 2006-2007, 2010, 2012 The University of Melbourne.
+# Copyright (C) 2014, 2019, 2022-2023 The Mercury team.
  # This file may only be copied under the terms of the GNU General
  # Public Licence - see the file COPYING in the Mercury distribution.
  #-----------------------------------------------------------------------------#
@@ -20,11 +21,11 @@ include $(MERCURY_DIR)/Mmake.common

  .PHONY: lib$(GC_GRADE)

-ifneq ("$(filter nogc mps,$(GC_GRADE))","")
+ifneq ("$(filter nogc,$(GC_GRADE))","")

  # No need to build the Boehm garbage collector for grades which don't use it
  # (this includes the .NET and Java backends, and for the C backend
-# grades with `--gc none', `--gc mps', or `--gc accurate').
+# grades with `--gc none' or `--gc accurate').

  lib$(GC_GRADE):

@@ -69,7 +70,7 @@ submake: force
  else
  submake: force
  	MAKEFLAGS=""; export MAKEFLAGS; \
-	nmake -f NT_MAKEFILE cdebug="$(CDEBUG)" nodebug=1 CPU=x86 MAKE_AS_LIB=1 gc.lib; \
+	nmake -f NT_MAKEFILE cdebug="$(CDEBUG)" nodebug=1 CPU="$(BOEHM_WINDOWS_CPU_TYPE)" MAKE_AS_LIB=1 gc.lib; \
  	cp gc.lib lib$(GC_GRADE).lib
  endif

@@ -172,7 +173,7 @@ install_dirs:
  	-[ -d $(INSTALL_MERC_GC_LIB_DIR) ] || \
  		mkdir -p $(INSTALL_MERC_GC_LIB_DIR)

-ifneq ("$(filter nogc mps,$(GC_GRADE))","")
+ifneq ("$(filter nogc,$(GC_GRADE))","")

  # No need to install the Boehm collector for grades which don't use it.