1. The $< target[1] does not work for regular rules and is
expanded to an empty string after issuing the warning
NMAKE : warning U4006: special macro undefined : '$<"'
Solution: replace $< by $?
2. The substitution regex is not quoted correctly, which leads
to the following error message by cmd.exe:
'href' is not recognized as an internal or external command,
operable program or batch file.
Solution: Quoting arguments for cmd.exe is really a nightmare,
but with the help of the excellent description [2] I was able to
properly quote the regex. Things were complicated by the fact that
a lot of levels of unquoting needed to be considered:
* perl (windows-makefile.tmpl -> makefile)
* make (reading the makefile)
* cmd.exe (executed by make)
* perl (scanning command line using CommandLineToArgvW())
The fix works, but the regex has become unmaintainable. It would actually
be better to wrap the entire command (including the regex) into a little
perl script which can be called by make directly.