[CRT_APITEST] Fix tests for wctomb

- Dynamically load function from the appropriate DLL
- Remove from ntdll_apitest (these are not exported by ntdll)

modules/rostests/apitests/crt/wctomb.c

···
 #define todo_static todo_if(1)
 #else
 #define todo_static
+typedef int (__cdecl *PFN_wctomb)(char *mbchar, wchar_t wchar);
+static PFN_wctomb p_wctomb;
+
+static BOOL Init(void)
+{
+    HMODULE hdll = LoadLibraryA(TEST_DLL_NAME);
+    p_wctomb = (PFN_wctomb)GetProcAddress(hdll, "wctomb");
+    ok(p_wctomb != NULL, "Failed to load wctomb from %s\n", TEST_DLL_NAME);
+    return (p_wctomb != NULL);
+}
+#define wctomb p_wctomb
 #endif
 
 START_TEST(wctomb)
···
     char *loc;
     unsigned int codepage = ___lc_codepage_func();
     wchar_t wchSrc[2] = {L'R', 0414}; // 0414 corresponds to a Russian character in Windows-1251
+
+#ifndef TEST_STATIC_CRT
+    if (!Init())
+    {
+        skip("Skipping tests, because wctomb is not available\n");
+        return;
+    }
+#endif
 
     chDest = AllocateGuarded(sizeof(*chDest));
     if (!chDest)

modules/rostests/apitests/ntdll/CMakeLists.txt

···
     ../crt/_vsnprintf.c
     ../crt/_vsnwprintf.c
     ../crt/mbstowcs.c
-    ../crt/mbtowc.c
     ../crt/setjmp.c
     ../crt/sprintf.c
     ../crt/strcpy.c
···
     ../crt/strtoul.c
     ../crt/wcstombs.c
     ../crt/wcstoul.c
-    ../crt/wctomb.c
 )
 
 add_library(ntdll_crt_test_lib ${SOURCE_CRT_TESTS})

modules/rostests/apitests/ntdll/testlist.c

···
 extern void func__vsnprintf(void);
 extern void func__vsnwprintf(void);
 extern void func_mbstowcs(void);
-extern void func_mbtowc(void);
 extern void func_setjmp(void);
 extern void func_sprintf(void);
 extern void func_strcpy(void);
 extern void func_strlen(void);
 extern void func_strtoul(void);
 extern void func_wcstoul(void);
-extern void func_wctomb(void);
 extern void func_wcstombs(void);
 
 extern void func_DllLoadNotification(void);
···
     { "_vsnprintf", func__vsnprintf },
     { "_vsnwprintf", func__vsnwprintf },
     { "mbstowcs", func_mbstowcs },
-    { "mbtowc", func_mbtowc },
     { "setjmp", func_setjmp },
     { "sprintf", func_sprintf },
     { "strcpy", func_strcpy },
     { "strlen", func_strlen },
     { "strtoul", func_strtoul },
     { "wcstoul", func_wcstoul },
-    { "wctomb", func_wctomb },
     { "wcstombs", func_wcstombs },
 
     { "DllLoadNotification",            func_DllLoadNotification },