Fixed type.

[[Imported from SVN: r6481]]

m4/dune_boost_base.m4

@@ -26,7 +26,7 @@ AC_DEFUN([DUNE_BOOST_BASE],
 [
 AX_BOOST_BASE([$1],[
   AC_DEFINE(HAVE_BOOST, [ENABLE_BOOST],[Define to ENABLE_BOOST if the Boost library is available])
-  BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DENBABLE_BOOST"
+  BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DENABLE_BOOST"
   AC_SUBST(BOOST_CPPFLAGS)
   # execute ACTION-IF-FOUND (if present):
   ifelse([$2], , :, [$2])