- Let users compile Python with DTrace support. The option is off by
default for now.
- Set USES=gmake. It turns out that the Python makefiles contain syntax
specific to GNU make, which is interpreted by bmake in an unexptected way (in
particular, $< is not expanded as desired). In order to fix that, let's just
use GNU make for now.
- Patch the configure script in order to force building of the object files
required for DTrace support. Here's the problem with the detection mechanism:
```
$ dtrace -G -s ./conftest.d -xnolibs -o /tmp/conftest.o
ld: error: /usr/lib/dtrace/drti.o is incompatible with /tmp/conftest.o.0DHcqI
dtrace: failed to link script ./conftest.d: failed to link /tmp/conftest.o: ld exited with status 1
```
Related:
- https://bugs.python.org/issue29077