POSIX requires that the value of SHELL in the makefile NOT be exported
to sub-commands. Instead, the value in the environment when make was
invoked should be passed to the environment of sub-commands. Note that
make still uses SHELL to _run_ sub-commands; it just doesn't change the
value of the SHELL variable in the environment of sub-commands.
As an extension to POSIX, if the makefile explicitly exports SHELL then
GNU make _will_ use it in the environment of sub-commands.
* Never use "touch" in make rules; it breaks on most sub-second
supporting systems. Use echo "" > $@ instead.
* Forgot to close test makefiles before using them!
All the above worked fine on Linux but failed miserably on Solaris.
New version of the manual, put into the doc subdir.
Enhancements: $(eval ...) and $(value ...) functions, various bug
fixes, etc. See the ChangeLog.
More to come.