libmicrohttpd: Building 0.9.24 fails on missing .texi files

The autoreconf triggers texinfo targets to be regenerated if possible.
This will not be a problem if /usr/bin/makeinfo is missing from the
system. However, if there is makeinfo then you get this:

$ ./scripts/build libmicrohttpd
...
rm -rf $backupdir; exit $rc
libmicrohttpd.texi:2132: @include `lgpl.texi': No such file or directory.
libmicrohttpd.texi:2136: @include `ecos.texi': No such file or directory.
libmicrohttpd.texi:2140: @include `fdl-1.3.texi': No such file or directory.
makeinfo: Removing output file `libmicrohttpd.info' due to errors; use --force to preserve.
make[1]: *** [libmicrohttpd.info] Error 1

Since the upstream tarball is being built as it is, avoiding the
reconfigure solves the issue.