test: Add run-tests-exp.sh, script to run testsuite with only sh dependency.

This script uses expected test results as generated by run-tests --write-exp,
and requires only standard unix shell funtionality (no bash). It is useful
to run testsuite on embedded systems, where there's no CPython and Bash.

tests/run-tests-exp.sh

+#!/bin/sh
+#
+# This is plain shell variant of run-tests script, which uses .exp files
+# as generated by run-tests --write-exp. It is useful to run testsuite
+# on embedded systems which doesn't have CPython3.
+#
+
+RM="rm -f"
+MP_PY=micropython
+
+numtests=0
+numtestcases=0
+numpassed=0
+numfailed=0
+namefailed=
+
+if [ $# -eq 0 ]
+then
+    tests="basics/*.py micropython/*.py float/*.py import/*.py io/*.py misc/*.py"
+else
+    tests="$@"
+fi
+
+for infile in $tests
+do
+    basename=`basename $infile .py`
+    outfile=${basename}.out
+    expfile=$infile.exp
+
+    $MP_PY $infile > $outfile
+    numtestcases=$(expr $numtestcases + $(cat $expfile | wc -l))
+
+    diff --brief $expfile $outfile > /dev/null
+
+    if [ $? -eq 0 ]
+    then
+        echo "pass  $infile"
+        $RM $outfile
+        numpassed=$(expr $numpassed + 1)
+    else
+        echo "FAIL  $infile"
+        numfailed=$(expr $numfailed + 1)
+        namefailed="$namefailed $basename"
+    fi
+
+    numtests=$(expr $numtests + 1)
+done
+
+echo "$numtests tests performed ($numtestcases individual testcases)"
+echo "$numpassed tests passed"
+if [ $numfailed != 0 ]
+then
+    echo "$numfailed tests failed -$namefailed"
+    exit 1
+else
+    exit 0
+fi