Fix quoting bug in --without-export implementation.
diff --git a/configure.ac b/configure.ac
index 8c13082..c270662 100644
--- a/configure.ac
+++ b/configure.ac
@@ -475,7 +475,7 @@
 AC_ARG_WITH([export],
   [AS_HELP_STRING([--without-export], [disable exporting jemalloc public APIs])],
   [if test "x$with_export" = "xno"; then
-  AC_DEFINE([JEMALLOC_EXPORT],[])]
+  AC_DEFINE([JEMALLOC_EXPORT],[])
 fi]
 )