Fix most shell hygiene issues found by shellcheck

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

src/tests/emulation-multiline-scroll.test

@@ -7,11 +7,12 @@
 # 24 in this test environment).
 #
 
-. $(dirname $0)/e2e-test-subrs
+# shellcheck source=e2e-test-subrs
+. "$(dirname "$0")/e2e-test-subrs"
 PATH=$PATH:.:$srcdir
 # Top-level wrapper.
 if [ $# -eq 0 ]; then
-    e2e-test $0 baseline
+    e2e-test "$0" baseline
     exit
 fi
 
@@ -25,8 +26,8 @@ baseline()
     printf '\033[H\033[J'
     for dir in L M; do
 	for i in $(seq 0 2) $(seq 22 26); do
-	    printf '%d\r' $i
-	    printf '\033[%d%s' $i $dir
+	    printf '%d\r' "$i"
+	    printf '\033[%d%s' "$i" "$dir"
 	    # On the one hand, we'd like to test that this works
 	    # properly on both client and server, which requires
 	    # delays so that each iteration percolates to the client
@@ -41,5 +42,5 @@ case $1 in
     baseline)
 	baseline;;
     *)
-	fail "unknown test argument %s\n" $1;;
+	fail "unknown test argument %s\n" "$1";;
 esac