pythongh-109575: Don't export -fsanitize compiler options

When Python is configured to use ASAN, MSAN or UBSAN sanitizer, with
"./configure --with-address-sanitizer" for example, compiler and
linker flags for sanitizers are no longer exported to third party C
extensions. Add flags to CFLAGS_NODIST and LDFLAGS_NODIST, instead of
BASECFLAGS and LDFLAGS.

Makefile.pre.in: PY_LDFLAGS_NOLTO now uses PY_LDFLAGS_NODIST, instead
of LDFLAGS_NODIST.

Makefile.pre.in

@@ -107,7 +107,7 @@ PY_CFLAGS_NODIST=$(CONFIGURE_CFLAGS_NODIST) $(CFLAGS_NODIST) -I$(srcdir)/Include
 PY_CPPFLAGS=	$(BASECPPFLAGS) -I. -I$(srcdir)/Include $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)
 PY_LDFLAGS=	$(CONFIGURE_LDFLAGS) $(LDFLAGS)
 PY_LDFLAGS_NODIST=$(CONFIGURE_LDFLAGS_NODIST) $(LDFLAGS_NODIST)
-PY_LDFLAGS_NOLTO=$(PY_LDFLAGS) $(CONFIGURE_LDFLAGS_NOLTO) $(LDFLAGS_NODIST)
+PY_LDFLAGS_NOLTO=$(PY_LDFLAGS) $(CONFIGURE_LDFLAGS_NOLTO) $(PY_LDFLAGS_NODIST)
 NO_AS_NEEDED=	@NO_AS_NEEDED@
 CCSHARED=	@CCSHARED@
 # LINKFORSHARED are the flags passed to the $(CC) command that links

Misc/NEWS.d/next/Build/2023-09-19-16-32-56.gh-issue-109575.41o1jt.rst

@@ -0,0 +1,5 @@
+When Python is configured to use ASAN, MSAN or UBSAN sanitizer, with
+``./configure --with-address-sanitizer`` for example, compiler and linker
+flags for sanitizers are no longer exported to third party C extensions. Add
+flags to ``CFLAGS_NODIST`` and ``LDFLAGS_NODIST``, instead of ``BASECFLAGS``
+and ``LDFLAGS``.  Patch by Victor Stinner.

configure.ac

@@ -2997,8 +2997,8 @@ AC_ARG_WITH([address_sanitizer],
                            [enable AddressSanitizer memory error detector, 'asan' (default is no)]),
 [
 AC_MSG_RESULT([$withval])
-BASECFLAGS="-fsanitize=address -fno-omit-frame-pointer $BASECFLAGS"
-LDFLAGS="-fsanitize=address $LDFLAGS"
+CFLAGS_NODIST="$CFLAGS_NODIST -fsanitize=address -fno-omit-frame-pointer"
+LDFLAGS_NODIST="$LDFLAGS_NODIST -fsanitize=address"
 # ASan works by controlling memory allocation, our own malloc interferes.
 with_pymalloc="no"
 ],
@@ -3014,8 +3014,8 @@ AC_ARG_WITH(
 [
 AC_MSG_RESULT([$withval])
 AX_CHECK_COMPILE_FLAG([-fsanitize=memory],[
-BASECFLAGS="-fsanitize=memory -fsanitize-memory-track-origins=2 -fno-omit-frame-pointer $BASECFLAGS"
-LDFLAGS="-fsanitize=memory -fsanitize-memory-track-origins=2 $LDFLAGS"
+CFLAGS_NODIST="$CFLAGS_NODIST -fsanitize=memory -fsanitize-memory-track-origins=2 -fno-omit-frame-pointer"
+LDFLAGS_NODIST="$LDFLAGS_NODIST -fsanitize=memory -fsanitize-memory-track-origins=2"
 ],[AC_MSG_ERROR([The selected compiler doesn't support memory sanitizer])])
 # MSan works by controlling memory allocation, our own malloc interferes.
 with_pymalloc="no"
@@ -3031,8 +3031,8 @@ AC_ARG_WITH(
   )],
 [
 AC_MSG_RESULT([$withval])
-BASECFLAGS="-fsanitize=undefined $BASECFLAGS"
-LDFLAGS="-fsanitize=undefined $LDFLAGS"
+CFLAGS_NODIST="$CFLAGS_NODIST -fsanitize=undefined"
+LDFLAGS_NODIST="$LDFLAGS_NODIST -fsanitize=undefined"
 with_ubsan="yes"
 ],
 [