Restarting poudriere

Thanks to much support on the lists it looks like poudriere _almost_
worked on the Pi3. 

In earlier tries builds of llvm10 failed from lack of memory. Restraining
poudriere with -J 2 and MAKE_JOBS_NUMBER=2 in /etc/make.conf, along with
turning off use of tmpfs appears to have relieved the excess memory pressure.

Restarting the poudriere session still fails with llvm10, reporting

c++: error: no such file or directory: '/wrkdirs/usr/ports/devel/llvm10/work/llvm-10.0.1.src/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp'
c++: error: no input files
ninja: build stopped: subcommand failed.
*** Error code 1

Similarly, the build of rust stopped with

10: fatal error: 'PPCTargetMachine.h' file not found
#include "PPCTargetMachine.h"
         ^~~~~~~~~~~~~~~~~~~~
1 error generated.
ninja: build stopped: subcommand failed.
thread 'main' panicked at '
command did not execute successfully, got: exit code: 1

It looks like artifacts from the previous build failures are somehow
persisting into subsequent work. There are no indications of memory
or swap insufficiency. 

Can anybody suggest a fix, short of starting over from scratch?
Perhaps building the offending packages individually, or in separate
jails? I've been using the same jail for all attempts so far.

Thanks for reading, and everyone's help!

bob prohaska