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

[vstinner]

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, and add CONFIGURE_LDFLAGS_NOLTO after PY_LDFLAGS_NODIST.

• Issue: ./configure --with-address-sanitizer adds -fsanitize flags to CFLAGS/LDFLAGS used by 3rd party C extensions #109575

[vstinner]

On the main branch, with the bug:

$ ./configure --with-pydebug --with-address-sanitizer CC=clang $ grep fsanitize Makefile BASECFLAGS= -fsanitize=address -fno-omit-frame-pointer -fno-strict-overflow -Wsign-compare -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer CONFIGURE_LDFLAGS= -fsanitize=address 

With the fix, the flags are not longer exported:

$ ./configure --with-pydebug --with-address-sanitizer CC=clang $ grep fsanitize Makefile CONFIGURE_CFLAGS_NODIST= -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -fsanitize=address -fno-omit-frame-pointer CONFIGURE_LDFLAGS_NODIST= -fsanitize=address 

[vstinner]

cc @gpshead@erlend-aasland

[vstinner]

Test PY_LDFLAGS_NOLTO on building _bootstrap_python:

./configure --with-address-sanitizer --with-lto make 

Logs:

gcc -flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none -g -fsanitize=address -fno-lto -o _bootstrap_python (...) 

-fno-lto option is passed as expected.

[gpshead]

this change makes sense if we want to do this. it wasn't clear what "right" behavior was to me for this, see my comment on the Issue. (i'm happy either way myself)

[vstinner]

I thought that it was a mistake, but apparently, some people actually want this behavior. I'm mostly using ASAN, but for ASAN, it seems to be the expected behavior. So I just close my PR :-)

If someone wants to adjust the code for other sanitizers, please go ahead!