Portable tst suites (awk trim instead of GNU tac) for macOS compatibility

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tst/cond_test.sh

@@ -31,7 +31,7 @@ bold=$'\033[1m'
 reset=$'\033[0m'
 
 # strip leading/trailing blank lines and surrounding whitespace
-trim() { sed -e 's/[[:space:]]*$//' | sed -e '/./,$!d' | tac | sed -e '/./,$!d' | tac; }
+trim() { awk '{ sub(/[ \t\r]+$/, "") } { line[NR]=$0 } END { f=1; while (f<=NR && line[f]=="") f++; l=NR; while (l>=1 && line[l]=="") l--; for (i=f;i<=l;i++) print line[i] }'; }
 
 # check_eq TEST_NAME EXPECTED KTEXT_ARGS...
 #   Runs ktext, expects exit status 0, and compares trimmed stdout to EXPECTED.