crt: tests: update t_winmain_assert

It is unclear what is the purpose of t_winmain_assert; it could be a simple
test program to observe behavior of assert() in an application using `WinMain`
as the entry point.

While this test uses `WinMain` as its entry point, it does not actually create
any windows, which allows to run it just like any other test program.

Update test test to assert that `lpCmdLine` argument is non-NULL.

Add t_winmain_assert to testcases/Makefile.am.

Signed-off-by: Kirill Makurin <maiddaisuki@outlook.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>

mingw-w64-crt/testcases/Makefile.am

diff --git a/mingw-w64-crt/testcases/Makefile.am b/mingw-w64-crt/testcases/Makefile.am
index bea64c0..58eaf81 100644
--- a/mingw-w64-crt/testcases/Makefile.am
+++ b/mingw-w64-crt/testcases/Makefile.am
@@ -103,6 +103,7 @@
   t_wcstok_s \
   t_wctob \
   t_wctype \
+  t_winmain_assert \
   t_wreaddir
 
 # FIXME: the following tests are disabled on arm64ec; linking them statically

mingw-w64-crt/testcases/t_winmain_assert.c

diff --git a/mingw-w64-crt/testcases/t_winmain_assert.c b/mingw-w64-crt/testcases/t_winmain_assert.c
index a690c31..6b9f10a 100644
--- a/mingw-w64-crt/testcases/t_winmain_assert.c
+++ b/mingw-w64-crt/testcases/t_winmain_assert.c
@@ -4,14 +4,12 @@
  * No warranty is given; refer to the file DISCLAIMER.PD within this package.
  */
 #include <assert.h>
-#include <string.h>
 
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
 int WINAPI WinMain(HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
 {
-  int argc = strlen (lpCmdLine);
-  assert (argc & 1);
+  assert (lpCmdLine != NULL);
   return 0;
 }