kBuild: incorrect expansion during template inheritance

[bird]

src/VBox/Main/webservices/Makefile.kmk in VirtualBox? exposes a problem where the simple vboxwebsrv_INCS := ... assignment causes the template INCS to be expanded at inherit time. The problem is that PATH_TOOL_VCC80AMD64_ATLMFC_INC isn't defined at that point. Changing the assignment to a recursive one vboxwebsrv_INCS = ... works around the problem.

[bird]

/utils/Makefile.kmk also seems to suffer from this wrt. to a LIBS.win prop that includes some DXSDK paths. It gets expanded before the SDK is loaded.

[bird]

(In [2007]) footer.kmk,tests: Convert simple variables into recursive ones by means of a helper variable during inheritance. This fixes the problem with forward references in a template when the target defined the property(.keyword) using a simple assignmnet. Fixes #51.

[bird]

Just a little side note, the fix increases the time spent doing template expansion (or template->target inheritance if you like). This is a prime candidate for a new helper function since it will certainly save a whole bunch of variable lookups and the need to use a helper variable to convert from simple to recursive flavor.

[bird]

Fixed the template expansion penalty introduced here by rewriting it in C, the result is a 10x speedup of this operation. Neath.