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.

windows/CMakeLists.txt

@@ -188,3 +188,14 @@ target_link_libraries(test_split_into_argv utils ${platform_libraries})
 add_executable(test_screenshot
   test_screenshot.c)
 target_link_libraries(test_screenshot utils ${platform_libraries})
+
+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
+  no-jump-list.c)
+target_link_libraries(test_lineedit
+  guiterminal settings eventloop utils ${platform_libraries})

windows/platform.h

@@ -195,6 +195,7 @@ void centre_window(HWND hwnd);
 #define DEFAULT_CODEPAGE CP_ACP
 #define USES_VTLINE_HACK
 #define CP_UTF8 65001
+#define CP_437 437                     /* used for test suites */
 
 #ifndef NO_GSSAPI
 /*