Bump minimum required Bison version to 2.4

This lets us replace the deprecated `%pure-parser` directive with
`%define api.pure`, and get rid of some other conditional code.

Bison is only required for developers hacking on the grammar, since we
check in the generated code.  Bison 2.4 was released in 2008, and is
included in operating systems as old as Red Hat Enterprise Linux 6.

1 files changed, 2 insertions, 2 deletions

diff --git a/perly.h b/perly.h
index 45cb6ba121..5a3cef7cf5 100644
--- a/perly.h
+++ b/perly.h
@@ -195,6 +195,6 @@ int yyparse (void);
 
 
 /* Generated from:
- * e5b801fdebce5c77dd8e644fc5a489cbea6af33db180e771dd9d669b12bbe0cf perly.y
- * 0947213b55d0ed11693554bea04987e886cf285f5c14cf9075fa1e7acc3f4061 regen_perly.pl
+ * f83d884147747f2d8f5a62eebc4ccd07d71b6b34e5ba1a8d7559526ad864dc97 perly.y
+ * 1b401b34e1842dd8814919ea427f1b13abc479699495e6e88f8fe4c7ab2f838f regen_perly.pl
  * ex: set ro: */