For the same reasons as set_config is being moved to the global scope,
we're moving set_define to the global scope here. An additional change
is that set_define is now part of the sandbox itself instead of being
defined within the sandbox, which makes it share the implementation
details with set_config.
The way set_config is set currently makes it difficult to introspect
moz.configure files to know what configuration items are being set,
because they're hidden in the control flow of functions.
This makes some of the moz.configure more convoluted, but this is why
there are templates, and we can improve the recurring cases afterwards.
old-configure and js/src/old-configure interestingly didn't handle both
the same way. But vtune support is only actually implemented in js/src,
so only the rules from js/src/old-configure matter (nothing was
enforcing the decistion from old-configure to js/src/old-configure), and
this is what is implemented here.
The implementation is a bit circumvoluted, but we do need to share
options between the top-level and js/src configures, possibly with
different defaults, and to properly pass things down from one to
the other. Until we are further down the road and can actually merge
both configures, this is a necessary evil.
Because --enable-application is the current way to do things, transpose
it to configure.py, but since --enable-application=js doesn't make
sense, make it an alias of a new --enable-project option.
This only partially moves --enable-application out of old-configure.in
because there are a lot of other things intertwined with it.
