config headers and #undefs

[Kevin Ryde]

I'm using AM_CONFIG_HEADER to insert a couple of configure-time
defines into headers which will be installed.  This works well, except
that I want to have one literal #undef pass through, rather than be
commented out like normally happens.

Perhaps a special marker could stop selected #undef's from getting
transformed, for instance,

        #define __need_size_t
        #include <stddef.h>
        #undef __need_size_t /*NOTATEMPLATE*/

acgeneral.m4.undef.diff
Description: Source code patch