style: don't use std::endl

* data/lalr1.cc, doc/bison.texi, etc/bench.pl.in, examples/variant.yy,
* tests/actions.at, tests/atlocal.in, tests/c++.at, tests/headers.at,
* tests/local.at, tests/types.at:
Don't use std::endl, it flushes uselessly, and is considered bad
style.

tests/headers.at

@@ -181,7 +181,7 @@ extern "C"
   do {                                          \
     int res = S;                                \
     if (res)                                    \
-      std::cerr << #S": " << res << std::endl;  \
+      std::cerr << #S": " << res << '\n';       \
   } while (false)
 
 int