gh-114099: Refactor configure and Makefile to accomodate non-macOS frameworks (#115120)

Part of the PEP 730 work to add iOS support.

This change lays the groundwork for introducing iOS/tvOS/watchOS 
frameworks; it includes the structural refactoring needed so that iOS
branches can be added into in a subsequent PR.

Summary of changes:
* Updates config.sub to the 2024-01-01 release. This is the "as 
  released" version of config.sub.
* Adds a RESSRCDIR variable to allow sharing of macOS and iOS Makefile 
  steps.
* Adds an INSTALLTARGETS variable so platforms can customise which
  targets are actually installed. This will be used to exclude certain
  targets (e.g., binaries, manfiles) from iOS framework installs.
* Adds a PYTHONFRAMEWORKINSTALLNAMEPREFIX variable; this is used as
  the install name for the library. This is needed to allow for iOS
  frameworks to specify an @rpath-based install name.
* Evaluates MACHDEP earlier in the configure process so that
  ac_sys_system is available.
* Modifies _PYTHON_HOST_PLATFORM evaluation for cross-platform builds
  so that the CPU architecture is differentiated from the host
  identifier. This will be used to generate a _PYTHON_HOST_PLATFORM
  definition that includes ABI information, not just CPU architecture.
* Differentiates between SOABI_PLATFORM and PLATFORM_TRIPLET.
  SOABI_PLATFORM is used in binary module names, and includes the ABI,
  but not the OS or CPU architecture (e.g.,
  math.cpython-313-iphonesimulator.dylib). PLATFORM_TRIPLET is used
  as the sys._multiarch value, and on iOS will contains the ABI and
  architecture (e.g., iphoneos-arm64). This differentiation hasn't
  historically been needed because while macOS is a multiarch platform,
  it uses a bare darwin as PLATFORM_TRIPLE.
* Removes the use of the deprecated -Wl,-single_module flag when
  compiling macOS frameworks.
* Some whitespace normalisation where there was a mix of spaces and tabs 
  in a single block.

Makefile.pre.in

@@ -184,6 +184,8 @@ PYTHONFRAMEWORK=	@PYTHONFRAMEWORK@
 PYTHONFRAMEWORKDIR=	@PYTHONFRAMEWORKDIR@
 PYTHONFRAMEWORKPREFIX=	@PYTHONFRAMEWORKPREFIX@
 PYTHONFRAMEWORKINSTALLDIR= @PYTHONFRAMEWORKINSTALLDIR@
+PYTHONFRAMEWORKINSTALLNAMEPREFIX= @PYTHONFRAMEWORKINSTALLNAMEPREFIX@
+RESSRCDIR= @RESSRCDIR@
 # Deployment target selected during configure, to be checked
 # by distutils. The export statement is needed to ensure that the
 # deployment target is active during build.
@@ -866,7 +868,7 @@ libpython3.so:	libpython$(LDVERSION).so
 	$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
 
 libpython$(LDVERSION).dylib: $(LIBRARY_OBJS)
-	 $(CC) -dynamiclib -Wl,-single_module $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(SHLIBS) $(LIBC) $(LIBM); \
+	 $(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(PYTHONFRAMEWORKINSTALLNAMEPREFIX)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(SHLIBS) $(LIBC) $(LIBM); \
 
 
 libpython$(VERSION).sl: $(LIBRARY_OBJS)
@@ -891,14 +893,13 @@ $(BUILDPYTHON)-gdb.py: $(SRC_GDB_HOOKS)
 # This rule is here for OPENSTEP/Rhapsody/MacOSX. It builds a temporary
 # minimal framework (not including the Lib directory and such) in the current
 # directory.
-RESSRCDIR=Mac/Resources/framework
 $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK): \
 		$(LIBRARY) \
 		$(RESSRCDIR)/Info.plist
 	$(INSTALL) -d -m $(DIRMODE) $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)
 	$(CC) -o $(LDLIBRARY) $(PY_CORE_LDFLAGS) -dynamiclib \
-		-all_load $(LIBRARY) -Wl,-single_module \
-		-install_name $(DESTDIR)$(PYTHONFRAMEWORKINSTALLDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK) \
+		-all_load $(LIBRARY) \
+		-install_name $(DESTDIR)$(PYTHONFRAMEWORKINSTALLNAMEPREFIX)/$(PYTHONFRAMEWORK) \
 		-compatibility_version $(VERSION) \
 		-current_version $(VERSION) \
 		-framework CoreFoundation $(LIBS);
@@ -2000,7 +2001,7 @@ multissltest: all
 # which can lead to two parallel `./python setup.py build` processes that
 # step on each others toes.
 .PHONY: install
-install: @FRAMEWORKINSTALLFIRST@ commoninstall bininstall maninstall @FRAMEWORKINSTALLLAST@
+install: @FRAMEWORKINSTALLFIRST@ @INSTALLTARGETS@ @FRAMEWORKINSTALLLAST@
 	if test "x$(ENSUREPIP)" != "xno"  ; then \
 		case $(ENSUREPIP) in \
 			upgrade) ensurepip="--upgrade" ;; \