tests: Build all tests with strict prototypes.

dlls/Maketest.rules.in

@@ -10,7 +10,7 @@
 #
 
 DLLFLAGS     = @DLLFLAGS@
-DEFS         = $(EXTRADEFS)
+DEFS         = -DWINE_STRICT_PROTOTYPES $(EXTRADEFS)
 
 MODULE       = $(TESTDLL:%.dll=%)_test.exe
 TESTRESULTS  = $(CTESTS:.c=.ok)

dlls/user32/tests/class.c

@@ -598,8 +598,8 @@ static void test_builtinproc(void)
     HWND hwnd;
     int i;
 
-    pDefWindowProcA = GetProcAddress(GetModuleHandle("user32.dll"), "DefWindowProcA");
-    pDefWindowProcW = GetProcAddress(GetModuleHandle("user32.dll"), "DefWindowProcW");
+    pDefWindowProcA = (void *)GetProcAddress(GetModuleHandle("user32.dll"), "DefWindowProcA");
+    pDefWindowProcW = (void *)GetProcAddress(GetModuleHandle("user32.dll"), "DefWindowProcW");
 
     for (i = 0; i < 4; i++)
     {