Move the dropped '--enable-layout' subdir logic into APR_SUBDIR_CONFIG macro

Move the dropped '--enable-layout' subdir logic into APR_SUBDIR_CONFIG macro
as a third parameter rather than manually computing it ourselves.

Add the ' prefix'd --enable-layout so that this can work with an autoconf-2.54+
generated configure.  (Previously, the option would not be dropped with 2.54
or 2.57 since it unconditionally adds single-quotes which our case statement
would not catch.)

Try to shorten long invocations of APR_SUBDIR_CONFIG where possible.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@99257 13f79535-47bb-0310-9956-ffa450edef68