Fix more fallout for bundled rocksdb after the LLVM 10 import

In file included from rocksdb/utilities/backupable/backupable_db.cc:16:
rocksdb/util/channel.h:35:33: error: no matching constructor for initialization of 'std::lock_guard<std::mutex>'
    std::lock_guard<std::mutex> lk(lock_);
                                ^  ~~~~~
/usr/include/c++/v1/__mutex_base:90:14: note: candidate constructor not viable: 1st argument ('const std::mutex') would lose const qualifier
    explicit lock_guard(mutex_type& __m) _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability(__m))
             ^
/usr/include/c++/v1/__mutex_base:100:5: note: candidate constructor not viable: no known conversion from 'const std::mutex' to 'const std::__1::lock_guard<std::__1::mutex>' for 1st argument
    lock_guard(lock_guard const&) _LIBCPP_EQUAL_DELETE;
    ^
/usr/include/c++/v1/__mutex_base:94:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
    lock_guard(mutex_type& __m, adopt_lock_t) _LIBCPP_THREAD_SAFETY_ANNOTATION(requires_capability(__m))
    ^
1 error generated.

net/ceph* will still not build because Clang crashes but at least
it goes beyond the above error.

1 files changed, 28 insertions, 0 deletions

diff --git a/databases/cockroach/files/patch-src_github.com_cockroachdb_cockroach_c-deps_rocksdb_util_channel.h b/databases/cockroach/files/patch-src_github.com_cockroachdb_cockroach_c-deps_rocksdb_util_channel.h
new file mode 100644
index 000000000000..87972bfbcf63
--- /dev/null
+++ b/databases/cockroach/files/patch-src_github.com_cockroachdb_cockroach_c-deps_rocksdb_util_channel.h
@@ -0,0 +1,28 @@
+In file included from rocksdb/utilities/backupable/backupable_db.cc:16:
+rocksdb/util/channel.h:35:33: error: no matching constructor for initialization of 'std::lock_guard<std::mutex>'
+    std::lock_guard<std::mutex> lk(lock_);
+                                ^  ~~~~~
+/usr/include/c++/v1/__mutex_base:90:14: note: candidate constructor not viable: 1st argument ('const std::mutex') would lose const qualifier
+    explicit lock_guard(mutex_type& __m) _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability(__m))
+             ^
+/usr/include/c++/v1/__mutex_base:100:5: note: candidate constructor not viable: no known conversion from 'const std::mutex' to 'const std::__1::lock_guard<std::__1::mutex>' for 1st argument
+    lock_guard(lock_guard const&) _LIBCPP_EQUAL_DELETE;
+    ^
+/usr/include/c++/v1/__mutex_base:94:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
+    lock_guard(mutex_type& __m, adopt_lock_t) _LIBCPP_THREAD_SAFETY_ANNOTATION(requires_capability(__m))
+    ^
+1 error generated.
+
+https://github.com/facebook/rocksdb/commit/a796c06fef6a8e43d793f8e627db3f29e6f95964
+
+--- src/github.com/cockroachdb/cockroach/c-deps/rocksdb/util/channel.h.orig	2018-04-13 11:22:33 UTC
++++ src/github.com/cockroachdb/cockroach/c-deps/rocksdb/util/channel.h
+@@ -62,7 +62,7 @@ class channel {
+ 
+  private:
+   std::condition_variable cv_;
+-  std::mutex lock_;
++  mutable std::mutex lock_;
+   std::queue<T> buffer_;
+   bool eof_;
+ };