build: call AC_PREREQ() first & quote argument

> This macro may be used before AC_INIT.

Calling this first means establishing that the required version of
autoconf is actually available, before bothering with AC_INIT().

See:
https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.67/autoconf.html#Versioning.

diff --git a/configure.ac b/configure.ac
index f7b5b5b5685b8eb4d6c7dfbcc4c05e50e9995466..3a526e248007dcc60233d42bd61c1cb7a744eb28 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -5,8 +5,8 @@ dnl See LICENSE for copying information.
 dnl
 dnl Original version Dug Song <dugsong@monkey.org>
 
+AC_PREREQ([2.67])
 AC_INIT(libevent,2.2.0-alpha-dev)
-AC_PREREQ(2.67)
 AC_CONFIG_SRCDIR(event.c)
 
 AC_CONFIG_MACRO_DIR([m4])