Merge bitcoin/bitcoin#29837: ci: disable _FORTIFY_SOURCE with MSAN

08ff17d ci: disable _FORTIFY_SOURCE with MSAN (fanquake)

Pull request description:

  By undefining `_FORTIFY_SOURCE` we can drop`--disable-hardening`.

ACKs for top commit:
  maflcko:
    lgtm ACK 08ff17d
  hernanmarino:
    utACK 08ff17d . Relevant CI test seems to be working OK.

Tree-SHA512: 948fd075aa648a7e34c37376fb913074ebc07d1c3cb0737d5fcbe7eac0b35c4152139773e4515ccb80f2d11b1ced6c6984da1757c2bcf8dd90e8ff6f664dae8e

Author: fanquake

ci/test/00_setup_env_native_fuzz_with_msan.sh

@@ -17,7 +17,8 @@ export PACKAGES="ninja-build"
 # BDB generates false-positives and will be removed in future
 export DEP_OPTS="DEBUG=1 NO_BDB=1 NO_QT=1 CC=clang CXX=clang++ CFLAGS='${MSAN_FLAGS}' CXXFLAGS='${MSAN_AND_LIBCXX_FLAGS}'"
 export GOAL="install"
-export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer,memory --disable-hardening CPPFLAGS='-DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE'"
+# _FORTIFY_SOURCE is not compatible with MSAN.
+export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer,memory CPPFLAGS='-DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE -U_FORTIFY_SOURCE'"
 export USE_MEMORY_SANITIZER="true"
 export RUN_UNIT_TESTS="false"
 export RUN_FUNCTIONAL_TESTS="false"

ci/test/00_setup_env_native_msan.sh

@@ -17,7 +17,8 @@ export PACKAGES="ninja-build"
 # BDB generates false-positives and will be removed in future
 export DEP_OPTS="DEBUG=1 NO_BDB=1 NO_QT=1 CC=clang CXX=clang++ CFLAGS='${MSAN_FLAGS}' CXXFLAGS='${MSAN_AND_LIBCXX_FLAGS}'"
 export GOAL="install"
-export BITCOIN_CONFIG="--with-sanitizers=memory --disable-hardening"
+# _FORTIFY_SOURCE is not compatible with MSAN.
+export BITCOIN_CONFIG="--with-sanitizers=memory CPPFLAGS='-U_FORTIFY_SOURCE'"
 export USE_MEMORY_SANITIZER="true"
 export RUN_FUNCTIONAL_TESTS="false"
 export CCACHE_MAXSIZE=250M