hbytes.h: Add a missing `extern' on a data declaration

With GCC-10's changes to the default symbol resolution rules, the
absence leads to this error:
  /usr/bin/ld: hbytes.o:/<<PKGBUILDDIR>>/hbytes/hbytes.h:251: multiple definition of `cht_ulong_type'; chop.o:/<<PKGBUILDDIR>>/hbytes/hbytes.h:251: first defined here
(once per object file).

Closes: 957087
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/hbytes/hbytes.h b/hbytes/hbytes.h
index 0ed871c8f3d20a1e3ef9b64586fc4c878304d57e..2e5d658914c0286265fed4de858c7ee72e325ff7 100644 (file)
--- a/hbytes/hbytes.h
+++ b/hbytes/hbytes.h
@@ -248,7 +248,7 @@ extern Tcl_ObjType cht_addrmap_type;
 
 /* from ulong.c */
 
-Tcl_ObjType cht_ulong_type;
+extern Tcl_ObjType cht_ulong_type;
 
 /* useful macros */