Modify the NTMakefile rules for tests so that a failed test does
not prevent subsequent tests from being executed.
Change-Id: I9595ad4a1527feae7c402241bf06ab21a0b76d4a
Once DLLs and EXEs are built, they need to have their manifests
processed and signed. These steps are encapsulated in the EXEPREP and
DLLPREP Makefile macros. Use them instead of invoking each processing
macro individually.
