kconfig: re-sync with Linux 4.10

Re-sync all files under the scripts/kconfig directory with
Linux 4.10.

Some parts include U-Boot own modification.  I made sure to not
revert the following commits:

 5b8031ccb4ed ("Add more SPDX-License-Identifier tags")
 192bc6948b02 ("Fix GCC format-security errors and convert sprintfs.")
 da58dec86616 ("Various Makefiles: Add SPDX-License-Identifier tags")
 20c20826efab ("Kconfig: Enable usage of escape char '\' in string values")

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/kconfig/zconf.l b/scripts/kconfig/zconf.l
index 6c62d93..c410d25 100644
--- a/scripts/kconfig/zconf.l
+++ b/scripts/kconfig/zconf.l
@@ -66,9 +66,16 @@
 	memcpy(text, str, size);
 	text[size] = 0;
 }
+
+static void warn_ignored_character(char chr)
+{
+	fprintf(stderr,
+	        "%s:%d:warning: ignoring unsupported character '%c'\n",
+	        zconf_curname(), zconf_lineno(), chr);
+}
 %}
 
-n	[A-Za-z0-9_]
+n	[A-Za-z0-9_-]
 
 %%
 	int str = 0;
@@ -106,7 +113,7 @@
 		zconflval.string = text;
 		return T_WORD;
 	}
-	.
+	.	warn_ignored_character(*yytext);
 	\n	{
 		BEGIN(INITIAL);
 		current_file->lineno++;
@@ -122,14 +129,17 @@
 	"!"	return T_NOT;
 	"="	return T_EQUAL;
 	"!="	return T_UNEQUAL;
+	"<="	return T_LESS_EQUAL;
+	">="	return T_GREATER_EQUAL;
+	"<"	return T_LESS;
+	">"	return T_GREATER;
 	\"|\'	{
 		str = yytext[0];
 		new_string();
 		BEGIN(STRING);
 	}
 	\n	BEGIN(INITIAL); current_file->lineno++; return T_EOL;
-	---	/* ignore */
-	({n}|[-/.])+	{
+	({n}|[/.])+	{
 		const struct kconf_id *id = kconf_id_lookup(yytext, yyleng);
 		if (id && id->flags & TF_PARAM) {
 			zconflval.id = id;
@@ -141,7 +151,8 @@
 	}
 	#.*	/* comment */
 	\\\n	current_file->lineno++;
-	.
+	[[:blank:]]+
+	.	warn_ignored_character(*yytext);
 	<<EOF>> {
 		BEGIN(INITIAL);
 	}