[project @ 2001-09-28 23:36:50 by sof]

[project @ 2001-09-28 23:36:50 by sof]
Provide finer-grained control for turning off mk/target.mk's
'all', 'boot' and 'install' rules. i.e., instead of having
the variable NO_ALL_TARGETS control the defnition of rules
for all three, NO_ALL_TARGET, NO_BOOT_TARGET, and NO_INSTALL_TARGET
lets you individually control which ones you don't want.

Sub-projects (GC and HDirect, for example) have the need
to turn off the 'boot' rule, which is what motivated this
change.