Log Message:
Rename one patch, add another to fix at least two problems preventing
this to build for NetBSD/powerpc:
 * need a cast in one place (in the renamed patch)
 * an overcautious assert() is incompatible with top/down VM layout in NetBSD
This still doesn't work on NetBSD/powerpc, though, and I ran out of time.
The build produces a mono-boehm.core file the first time through the build
(for some reason not the subsequent attempts, sigh!), and I have problems
reconstructing the CLI to run the mono-boehm executable under gdb, and the
core file says it got a segv in opendir() which must be nonsensical.