5156 - error-checking on writes to file

Pretty blunt for now; just abort the entire program on any failure to write.

I'm encountering it because I'm somehow treating a stream address as a
file descriptor. Maybe mmap is returning addresses below 0x08000000?

1 files changed, 0 insertions, 0 deletions

diff --git a/subx/apps/assort b/subx/apps/assort
index af7b47c2..3fbc3b7e 100755
--- a/subx/apps/assort
+++ b/subx/apps/assort
Binary files differ