Add a test rig for ldisc's local line editing.

I'm about to rewrite it completely, so the first thing I need to do is
to write tests for as much of the functionality as possible, so that I
can check the new implementation behaves in the same ways.

unix/CMakeLists.txt

@@ -226,3 +226,13 @@ target_link_libraries(pageant
   eventloop console agent settings network crypto utils
   ${pageant_libs})
 installed_program(pageant)
+
+add_executable(test_lineedit
+  ${CMAKE_SOURCE_DIR}/test/test_lineedit.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-gss.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-logging.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-printing.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-storage.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-timing.c)
+target_link_libraries(test_lineedit
+  guiterminal settings eventloop charset utils ${platform_libraries})

unix/platform.h

@@ -332,6 +332,7 @@ void gtk_setup_config_box(
  */
 #define DEFAULT_CODEPAGE 0xFFFF
 #define CP_UTF8 CS_UTF8                /* from libcharset */
+#define CP_437 CS_CP437                /* used for test suites */
 
 #define strnicmp strncasecmp
 #define stricmp strcasecmp