Merge bitcoin#11035: [contrib] Add Valgrind suppressions file

4a426d8 Add note about Valgrind suppressions file in developer-notes.md (practicalswift)
84e2462 contrib: Add Valgrind suppressions file (practicalswift)

Pull request description:

  Includes known Valgrind warnings in our dependencies that cannot be fixed in-tree.

  Example use:

  ```
  $ valgrind --suppressions=contrib/valgrind.supp src/test/test_bitcoin
  $ valgrind --suppressions=contrib/valgrind.supp --leak-check=full \
        --show-leak-kinds=all src/test/test_bitcoin --log_level=test_suite
  ```

  Running with the suppressions file under Ubuntu 16.04:

  ```
  $ valgrind --suppressions=contrib/valgrind.supp --leak-check=full --show-leak-kinds=all src/test/test_bitcoin --log_level=test_suite --run_test=wallet_crypto
  …
  ==10769== LEAK SUMMARY:
  ==10769==    definitely lost: 0 bytes in 0 blocks
  ==10769==    indirectly lost: 0 bytes in 0 blocks
  ==10769==      possibly lost: 0 bytes in 0 blocks
  ==10769==    still reachable: 0 bytes in 0 blocks
  ==10769==         suppressed: 72,704 bytes in 1 blocks
  ```

  Running without the suppressions file under Ubuntu 16.04:

  ```
  $ valgrind --leak-check=full --show-leak-kinds=all src/test/test_bitcoin --log_level=test_suite --run_test=wallet_crypto
  …
  ==10724== 72,704 bytes in 1 blocks are still reachable in loss record 1 of 1
  ==10724==    at 0x4C2DBF6: malloc (vg_replace_malloc.c:299)
  ==10724==    by 0x6F74EFF: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
  ==10724==    by 0x40106B9: call_init.part.0 (dl-init.c:72)
  ==10724==    by 0x40107CA: call_init (dl-init.c:30)
  ==10724==    by 0x40107CA: _dl_init (dl-init.c:120)
  ==10724==    by 0x4000C69: ??? (in /lib/x86_64-linux-gnu/ld-2.23.so)
  ==10724==    by 0x2: ???
  ==10724==    by 0x1FFF0006D2: ???
  ==10724==    by 0x1FFF0006E8: ???
  ==10724==    by 0x1FFF0006FF: ???
  ==10724==
  ==10724== LEAK SUMMARY:
  ==10724==    definitely lost: 0 bytes in 0 blocks
  ==10724==    indirectly lost: 0 bytes in 0 blocks
  ==10724==      possibly lost: 0 bytes in 0 blocks
  ==10724==    still reachable: 72,704 bytes in 1 blocks
  ==10724==         suppressed: 0 bytes in 0 blocks
  ```

Tree-SHA512: 9c92079fc61313ea678deb6aaa16a3a71c3154c757459793eb9ca0d90a9a74c6faebfb04c9135e1b398ca34224fb7f03bd9c488ea0e8debf6894f69f030a31d3

contrib/valgrind.supp

@@ -0,0 +1,43 @@
+# Valgrind suppressions file for Bitcoin.
+#
+# Includes known Valgrind warnings in our dependencies that cannot be fixed
+# in-tree.
+#
+# Example use:
+# $ valgrind --suppressions=contrib/valgrind.supp src/test/test_bitcoin
+# $ valgrind --suppressions=contrib/valgrind.supp --leak-check=full \
+#       --show-leak-kinds=all src/test/test_bitcoin --log_level=test_suite
+{
+   Suppress libstdc++ warning - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65434
+   Memcheck:Leak
+   match-leak-kinds: reachable
+   fun:malloc
+   obj:*/libstdc++.*
+   fun:call_init.part.0
+   fun:call_init
+   fun:_dl_init
+   obj:*/ld-*.so
+}
+{
+   Suppress libdb warning - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=662917
+   Memcheck:Cond
+   obj:*/libdb_cxx-*.so
+   fun:__log_put
+   obj:*/libdb_cxx-*.so
+   fun:__log_put_record
+}
+{
+   Suppress leveldb warning (leveldb::InitModule()) - https://github.com/google/leveldb/issues/113
+   Memcheck:Leak
+   match-leak-kinds: reachable
+   fun:_Znwm
+   fun:_ZN7leveldbL10InitModuleEv
+}
+{
+   Suppress leveldb warning (leveldb::Env::Default()) - https://github.com/google/leveldb/issues/113
+   Memcheck:Leak
+   match-leak-kinds: reachable
+   fun:_Znwm
+   ...
+   fun:_ZN7leveldbL14InitDefaultEnvEv
+}

doc/developer-notes.md

@@ -168,6 +168,21 @@ can be very difficult to track down. Compiling with -DDEBUG_LOCKORDER (configure
 CXXFLAGS="-DDEBUG_LOCKORDER -g") inserts run-time checks to keep track of which locks
 are held, and adds warnings to the debug.log file if inconsistencies are detected.
 
+**Valgrind suppressions file**
+
+Valgrind is a programming tool for memory debugging, memory leak detection, and
+profiling. The repo contains a Valgrind suppressions file
+([`valgrind.supp`](https://github.com/bitcoin/bitcoin/blob/master/contrib/valgrind.supp))
+which includes known Valgrind warnings in our dependencies that cannot be fixed
+in-tree. Example use:
+
+```shell
+$ valgrind --suppressions=contrib/valgrind.supp src/test/test_bitcoin
+$ valgrind --suppressions=contrib/valgrind.supp --leak-check=full \
+      --show-leak-kinds=all src/test/test_bitcoin --log_level=test_suite
+$ valgrind -v --leak-check=full src/bitcoind -printtoconsole
+```
+
 Locking/mutex usage notes
 -------------------------