Fix trivial_test

Apparently the non-w64 mingw32 does not have an swprintf function, though
it does have an snwprintf function.  In any case, the function takes a
second argument which is a buffer size.

Also include cwchar and cctype.

Print a message when building the test.

tests/Makefile

@@ -24,6 +24,7 @@ include ../config-mingw.mk
 LDFLAGS += -static-libgcc -static-libstdc++
 
 ../build/%.exe : %.cc
+	@echo Building $@
 	@$(CXX) $(CXXFLAGS) -std=c++11 -o $@ $^ $(LDFLAGS) ../build/winpty.dll
 
 TEST_PROGRAMS := \

tests/trivial_test.cc

@@ -19,11 +19,13 @@
 // IN THE SOFTWARE.
 
 #include <windows.h>
-#include <stdio.h>
-#include <stdlib.h>
 
-#include <vector>
 #include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <cwchar>
+#include <vector>
 
 #include "../include/winpty.h"
 #include "../shared/DebugClient.h"
@@ -86,7 +88,8 @@ static void parentTest() {
     wchar_t program[1024];
     wchar_t cmdline[1024];
     GetModuleFileNameW(NULL, program, 1024);
-    swprintf(cmdline, L"\"%s\" CHILD", program);
+    snwprintf(cmdline, sizeof(cmdline) / sizeof(cmdline[0]),
+              L"\"%s\" CHILD", program);
 
     winpty_t *pty = winpty_open(80, 25);
     assert(pty != NULL);