lemon: Add -- support to end options, use in our lemon

Patch lemon to stop parsing options upon encountering "--".
This prevents an issue in the unlikely situation where the
source directory or a source filename has a '=' in it, or
starts with a "-".

Redo 3716933046 but only
use the -- option in our lemon, not when using system lemon.

cmake/modules/UseLemon.cmake

@@ -21,7 +21,7 @@ if(LEMON_EXECUTABLE)
 	endmacro()
 	add_custom_target(lemon)
 else()
-	# Compile bundled lemon
+	# Compile bundled lemon with support for -- to end options
 	macro(generate_lemon_file _out _in)
 		add_custom_command(
 			OUTPUT
@@ -32,6 +32,7 @@ else()
 			COMMAND $<TARGET_FILE:lemon>
 				-T${CMAKE_SOURCE_DIR}/tools/lemon/lempar.c
 				-d.
+				--
 				${_in}
 			DEPENDS
 				${_in}

tools/lemon/lemon.c

@@ -2106,6 +2106,7 @@ int OptInit(char **a, struct s_options *o, FILE *err)
   if( g_argv && *g_argv && op ){
     int i;
     for(i=1; g_argv[i]; i++){
+      if( strcmp(g_argv[i],"--")==0 ) break;
       if( g_argv[i][0]=='+' || g_argv[i][0]=='-' ){
         errcnt += handleflags(i,err);
       }else if( strchr(g_argv[i],'=') ){

tools/lemon/patches/01-lemon-dashdash.patch

@@ -0,0 +1,14 @@
+Don't try to parse flags and options that are after "--". This makes it
+possible to prevent a filename path with an '=' in it from being processed
+as an option.
+SPDX-License-Identifier: CC0-1.0
+--- a/lemon.c
++++ b/lemon.c
+@@ -2106,6 +2106,7 @@ int OptInit(char **a, struct s_options *o, FILE *err)
+   if( g_argv && *g_argv && op ){
+     int i;
+     for(i=1; g_argv[i]; i++){
++      if( strcmp(g_argv[i],"--")==0 ) break;
+       if( g_argv[i][0]=='+' || g_argv[i][0]=='-' ){
+         errcnt += handleflags(i,err);
+       }else if( strchr(g_argv[i],'=') ){