acinclude.m4: fix typo

Author: tmatth

acinclude.m4

@@ -87,7 +87,7 @@ int main ()
        echo "*** If you have an old version installed, it is best to remove it, although"
        echo "*** you may also be able to get things to work by modifying LD_LIBRARY_PATH"],
        [ echo "*** The test program failed to compile or link. See the file config.log for the"
-       echo "*** exact error that occured. This usually means Ogg was incorrectly installed"
+       echo "*** exact error that occurred. This usually means Ogg was incorrectly installed"
        echo "*** or that you have moved Ogg since it was installed." ])
        CFLAGS="$ac_save_CFLAGS"
        LIBS="$ac_save_LIBS"