CBD-774: Add support for automake 1.13

Change-Id: I2ade1d84c778754a1b0fe96a61ad0716c2dd6d19
Reviewed-on: http://review.couchbase.org/23973
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>

configure.ac

@@ -25,7 +25,7 @@ AC_PROG_CC
 AM_PROG_CC_C_O
 AC_DISABLE_STATIC
 AC_PROG_LIBTOOL
-AM_CONFIG_HEADER([config.h])
+AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_MACRO_DIR([m4])
 
 # the malloc tests seems to be broken for cross compilation.. ignore them