Add an explicit "exit 0" to the shell scripts. This worked more or less by

coincidence before since shell scripts return the exit code of the last
command run if there is no explicit exit statement.

.github/checks/lastline.sh

@@ -23,3 +23,4 @@ if [ x"$FILES"x != xx ]; then
     done
     exit -1
 fi
+exit 0

.github/checks/lineendings.sh

@@ -16,3 +16,4 @@ if [ x"$FILES"x != xx ]; then
     done
     exit -1
 fi
+exit 0

.github/checks/noexec.sh

@@ -16,3 +16,4 @@ if [ x"$FILES"x != xx ]; then
     done
     exit -1
 fi
+exit 0

.github/checks/sorted.sh

@@ -36,3 +36,4 @@ function checkarray_quoted_name
 for N in `grep -rl "BEGIN SORTED.SH" "$CHECK_DIR"`; do
     checkarray_quoted_name $N
 done
+exit 0

.github/checks/sorted_codeopt.sh

@@ -66,3 +66,4 @@ function checkarray
 find "$CHECK_DIR" -name \*.\[ch\] -print | while read N; do
     grep -q "BEGIN DECL SORTED_CODEOPT.SH" "$N" && checkarray $N
 done
+exit 0	   

.github/checks/sorted_opcodes.sh

@@ -37,4 +37,4 @@ function checkarray_quoted_name
 for N in `grep -rl "BEGIN SORTED_OPCODES.SH" "$CHECK_DIR"`; do
     checkarray_quoted_name $N
 done
-
+exit 0

.github/checks/spaces.sh

@@ -16,3 +16,4 @@ if [ x"$FILES"x != xx ]; then
     done
     exit -1
 fi
+exit 0

.github/checks/tabs.sh

@@ -16,3 +16,4 @@ if [ x"$FILES"x != xx ]; then
     done
     exit -1
 fi
+exit 0