Merge changes from the Perl side

This contains many changes from https://80x24.org/mwrap-perl.git
commit

* Built-in RCU-friendly version of dlmalloc, no more fragile dlsym(3m)
  resolution of malloc-family functions in the constructor

* Allocations are now backed by O_TMPFILE on $TMPDIR on modern Linux.
  Since mwrap increases memory usage greatly and I needed to use it
  on a system where I needed more VM space but lacked the ability
  to add swap.

* Configurable C backtrace level via MWRAP=bt:$DEPTH where $DEPTH
  is a non-negative integer.  Be careful about increasing it, even
  a depth of 3-4 can be orders-of-magnitude more expensive in
  time and space.  This can be changed dynamically at runtime via
  local HTTP (see below).

* Embedded per-process local-socket-only HTTP server obsoletes
  MwrapRack when combined with mwrap-rproxy from the Perl dist
  (set `MWRAP=socket_dir:/dir/of/sockets')
  See https://80x24.org/mwrap-perl/20221210015518.272576-4-e@80x24.org/
  for more info.

  It now supports downloading CSV (suitable for importing into sqlite 3.32.0+)

* License switched to GPL-3+ to be compatible with GNU binutils
  since we may take code from addr2line in the future.

* libxxhash supported if XXH3_64bits is available.

1 files changed, 23 insertions, 0 deletions

diff --git a/ext/mwrap/check.h b/ext/mwrap/check.h
new file mode 100644
index 0000000..f4f4ac5
--- /dev/null
+++ b/ext/mwrap/check.h
@@ -0,0 +1,23 @@
+#ifndef CHECK_H
+#define CHECK_H
+#include "gcc.h"
+#include <stdlib.h>
+#include <assert.h>
+/*
+ * standard assert may malloc, but NDEBUG behavior is standardized,
+ * however Perl headers add some weirdness if we undef NDEBUG, so
+ * keep NDEBUG defined and use MWRAP_NO_DEBUG
+ */
+#if defined(NDEBUG) && defined(MWRAP_NO_DEBUG)
+#  define mwrap_assert(expr)
+#  define CHECK(type, expect, expr) (void)(expr)
+#else
+#  define mwrap_assert(x) do { if (caa_unlikely(!(x))) abort(); } while (0)
+#  define CHECK(type, expect, expr) do { \
+        type checkvar = (expr); \
+        mwrap_assert(checkvar==(expect)&& "BUG" && __FILE__ && __LINE__); \
+        (void)checkvar; \
+        } while (0)
+#endif
+
+#endif /* CHECK_H */