Merge bitcoin#14252: build: Run functional tests and benchmarks under…

… the undefined behaviour sanitizer (UBSan)

9f49db7 Enable functional tests in UBSAN job. Enable -fsanitize=integer (part of UBSAN). Merge UBSAN Travis job with no depends. (practicalswift)

Pull request description:

  Run functional tests and benchmarks under the undefined behaviour sanitizer (UBSan).

  This will make Travis automatically detect issues such as:
  * bitcoin#14242: Avoid triggering undefined behaviour (`std::memset(nullptr, 0, 0)`) if an invalid string is passed to `DecodeSecret(...)`
  * bitcoin#14239: Avoid dividing by zero (undefined behaviour) in `EstimateMedianVal` (policy)/`ConnectTip` (validation)/`CreateTransaction` (wallet)
  * bitcoin#13546: wallet: Avoid potential use of uninitialized value `bnb_used` in `CWallet::CreateTransaction(...)`

  Addresses issue bitcoin#14059.

Tree-SHA512: 285e1542b36c582516c47938ce8d999fd89ba6c867bc0976e7306e7c949b8b84ffbfa43dbc679dd97ae639b086092e7d799d8e1c903c66a37d529ce61d5c64b4

contrib/sanitizers-ubsan.suppressions

@@ -0,0 +1,27 @@
+alignment:move.h
+alignment:prevector.h
+bool:wallet/wallet.cpp
+float-divide-by-zero:policy/fees.cpp
+float-divide-by-zero:validation.cpp
+float-divide-by-zero:wallet/wallet.cpp
+nonnull-attribute:support/cleanse.cpp
+unsigned-integer-overflow:basic_string.h
+unsigned-integer-overflow:bench/bench.h
+unsigned-integer-overflow:bloom.cpp
+unsigned-integer-overflow:chain.h
+unsigned-integer-overflow:crypto/chacha20.cpp
+unsigned-integer-overflow:crypto/ctaes/ctaes.c
+unsigned-integer-overflow:crypto/ripemd160.cpp
+unsigned-integer-overflow:crypto/sha1.cpp
+unsigned-integer-overflow:crypto/sha256.cpp
+unsigned-integer-overflow:crypto/sha512.cpp
+unsigned-integer-overflow:hash.cpp
+unsigned-integer-overflow:leveldb/db/log_reader.cc
+unsigned-integer-overflow:leveldb/util/bloom.cc
+unsigned-integer-overflow:leveldb/util/crc32c.h
+unsigned-integer-overflow:leveldb/util/hash.cc
+unsigned-integer-overflow:policy/fees.cpp
+unsigned-integer-overflow:script/interpreter.cpp
+unsigned-integer-overflow:stl_bvector.h
+unsigned-integer-overflow:txmempool.cpp
+unsigned-integer-overflow:validation.cpp