Use SSize_t for read lock counter

We have tests to make sure this doesn't go negative, but wrongly
declared the variable as unsigned.

Spotted by Craig Berry.

1 files changed, 1 insertions, 1 deletions

diff --git a/perl.h b/perl.h
index cbb6905fe0..9627f3408c 100644
--- a/perl.h
+++ b/perl.h
@@ -3345,7 +3345,7 @@ typedef pthread_key_t	perl_key;
 typedef struct {
     perl_mutex lock;
     perl_cond  wakeup;
-    Size_t     readers_count;
+    SSize_t    readers_count;
 } perl_RnW1_mutex_t;