minikconf: explicitly set encoding to UTF-8

QEMU currently only has ASCII Kconfig files but Linux actually uses
UTF-8. Explicitly specify the encoding and that we're doing text file
I/O.

It's unclear whether or not QEMU will ever need Unicode in its Kconfig
files. If we start using the help text then it will become an issue
sooner or later. Make this change now for consistency with Linux
Kconfig.

Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200521153616.307100-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

scripts/minikconf.py

@@ -402,7 +402,7 @@ def do_include(self, include):
         if incl_abs_fname in self.data.previously_included:
             return
         try:
-            fp = open(incl_abs_fname, 'r')
+            fp = open(incl_abs_fname, 'rt', encoding='utf-8')
         except IOError as e:
             raise KconfigParserError(self,
                                 '%s: %s' % (e.strerror, include))
@@ -696,7 +696,7 @@ def scan_token(self):
             parser.do_assignment(name, value == 'y')
             external_vars.add(name[7:])
         else:
-            fp = open(arg, 'r')
+            fp = open(arg, 'rt', encoding='utf-8')
             parser.parse_file(fp)
             fp.close()
 
@@ -705,7 +705,7 @@ def scan_token(self):
         if key not in external_vars and config[key]:
             print ('CONFIG_%s=y' % key)
 
-    deps = open(argv[2], 'w')
+    deps = open(argv[2], 'wt', encoding='utf-8')
     for fname in data.previously_included:
         print ('%s: %s' % (argv[1], fname), file=deps)
     deps.close()