tests: Build all tests with strict prototypes.

dlls/Maketest.rules.in

diff --git a/dlls/Maketest.rules.in b/dlls/Maketest.rules.in
index aff002c..95f5c2b 100644
--- a/dlls/Maketest.rules.in
+++ b/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

diff --git a/dlls/user32/tests/class.c b/dlls/user32/tests/class.c
index f8a4cd8..0e7b0e4 100644
--- a/dlls/user32/tests/class.c
+++ b/dlls/user32/tests/class.c
@@ -598,8 +598,8 @@
     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++)
     {