Replace `seq` with POSIX-standard printf(1) in ManyAlternatives test

The test now passes on OpenBSD instead of generating broken source
which was rejected by GHC with

  ManyAlternatives.hs:5:1: error:
      The type signature for ‘f’ lacks an accompanying binding

1 files changed, 6 insertions, 4 deletions

diff --git a/testsuite/tests/perf/compiler/genManyAlternatives b/testsuite/tests/perf/compiler/genManyAlternatives
index 1035425bd4..6b5c79e036 100755
--- a/testsuite/tests/perf/compiler/genManyAlternatives
+++ b/testsuite/tests/perf/compiler/genManyAlternatives
@@ -24,11 +24,13 @@ MODULE=ManyAlternatives
 echo "module $MODULE where" > $MODULE.hs
 echo >> $MODULE.hs
 echo "data A$SIZE = A0" >> $MODULE.hs
-for i in $(seq -w 1 $SIZE); do
-  echo "  | A$i" >> $MODULE.hs
+i=1; while test $i -lt $SIZE; do
+  printf "  | A%03d\n" $i >> $MODULE.hs
+  i=$((i+1))
 done
 echo >> $MODULE.hs
 echo "f :: A$SIZE -> Int" >> $MODULE.hs
-for i in $(seq -w 1 $SIZE); do
-  echo "f A$i = 199$i" >> $MODULE.hs
+i=1; while test $i -lt $SIZE; do
+  printf "f A%03d = 199%03d\n" $i $i >> $MODULE.hs
+  i=$((i+1))
 done