Ignore errors from ulimit in sh_match.sh

Partial fix for #483

src/cmd/ksh93/tests/sh_match.sh

@@ -52,10 +52,11 @@ function test_xmlfragment1
     typeset -r testscript='test1_script.sh'
 
     cat >"${testscript}" <<-TEST1SCRIPT
-	# memory safeguards to prevent out-of-control memory consumption
-	ulimit -M \$(( 1024 * 1024 ))
-	ulimit -v \$(( 1024 * 1024 ))
-	ulimit -d \$(( 1024 * 1024 ))
+	# Put safeguards to prevent out-of-control memory consumption.
+	# Ignore "read only" error if a limit is not supported.
+	ulimit -M \$(( 1024 * 1024 )) 2>/dev/null
+	ulimit -v \$(( 1024 * 1024 )) 2>/dev/null
+	ulimit -d \$(( 1024 * 1024 )) 2>/dev/null
 
 	# input text
 	xmltext="\$( < "\$1" )"