run-tests: Test REPL emacs keys, but only if present.

Uses cmdline/repl_emacs_check.py to check for presence of emacs keys in
repl before doing full feature test.

tests/cmdline/repl_emacs_check.py

+# Check for emacs keys in REPL
+t = +11
+t == 2

tests/cmdline/repl_emacs_check.py.exp

+Micro Python \.\+ version
+>>> # Check for emacs keys in REPL
+>>> t = \.\+
+>>> t == 2
+True
+>>> 

tests/cmdline/repl_emacs_keys.py

+# REPL tests of GNU-ish readline navigation
+# history buffer navigation
+1
+2
+3
+
+
+# input line motion
+t = 12
+'boofar
fbar'

tests/cmdline/repl_emacs_keys.py.exp

+Micro Python \.\+ version
+>>> # REPL tests of GNU-ish readline navigation
+>>> # history buffer navigation
+>>> 1
+1
+>>> 2
+2
+>>> 3
+3
+>>> 321
+1
+>>> 1323
+3
+>>> # input line motion
+>>> t = 121
+>>> \.\+
+'foobar'
+>>> 

tests/run-tests

@@ -163,6 +163,12 @@ def run_tests(pyb, tests, args):
     if native == b'CRASH':
         skip_native = True
 
+    # Check if emacs repl is supported, and skip such tests if it's not
+    t = run_micropython(pyb, args, 'cmdline/repl_emacs_check.py')
+    if not 'True' in str(t, 'ascii'):
+        skip_tests.add('cmdline/repl_emacs_check.py')
+        skip_tests.add('cmdline/repl_emacs_keys.py')
+
     # Some tests shouldn't be run under Travis CI
     if os.getenv('TRAVIS') == 'true':
         skip_tests.add('basics/memoryerror.py')