[PATCH 1/2] Ractor compatibility

[Eric Wong <e@80x24.org>]

We can no longer depend on having GVL/GIL when we have a Ruby
execution context, so so make `kbuf' thread-specific to avoid
data corruption.

This was ported from the Perl5 version, since Perl5 has had
MVM/Ractor-like abilities with native threads for decades,
despite the Perl5 ecosystem largely avoids and discourages
threads.
---
 ext/mwrap/mwrap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c
index 1d6baec..90f560e 100644
--- a/ext/mwrap/mwrap.c
+++ b/ext/mwrap/mwrap.c
@@ -308,7 +308,9 @@ struct alloc_hdr {
 	size_t size;
 };
 
-static char kbuf[PATH_MAX + INT2STR_MAX + sizeof(struct alloc_hdr) + 2];
+static MWRAP_TSD char kbuf[
+	PATH_MAX + INT2STR_MAX + sizeof(struct alloc_hdr) + 2
+];
 
 static struct alloc_hdr *ptr2hdr(void *p)
 {