Deprecated/non-POSIX bison/yacc directives

[jdx-gh]

Similar to xflouris/libpll-2#22

Here is the patch:

diff --git a/src/tree/CMakeLists.txt b/src/tree/CMakeLists.txt
index ad2eb5f..30914cd 100644
--- a/src/tree/CMakeLists.txt
+++ b/src/tree/CMakeLists.txt
@@ -1,6 +1,6 @@
 find_package(BISON)
 find_package(FLEX)
-set(TREE_BISON_FLAGS "-y -d -p pllmod_utree_")
+set(TREE_BISON_FLAGS "-d -p pllmod_utree_")
 set(TREE_FLEX_FLAGS "-P pllmod_utree_")
 
 BISON_TARGET(split_utree_t 
diff --git a/src/tree/split_utree.y b/src/tree/split_utree.y
index ae69e03..56160b0 100644
--- a/src/tree/split_utree.y
+++ b/src/tree/split_utree.y
@@ -73,7 +73,7 @@ static void pllmod_utree_error(struct parse_params_t * paramas,
   void * nulval;
 }
 
-%error-verbose
+%define parse.error verbose
 
 %parse-param {void * params_ptr}
 %destructor { } subtree