crt: exe: Remove custom declaration of _initterm() function

Function _initterm() is declared in corecrt_startup.h.

Signed-off-by: Martin Storsjö <martin@martin.st>
diff --git a/mingw-w64-crt/crt/crtexe.c b/mingw-w64-crt/crt/crtexe.c
index 3d36983..7d5ba01 100644
--- a/mingw-w64-crt/crt/crtexe.c
+++ b/mingw-w64-crt/crt/crtexe.c
@@ -31,8 +31,6 @@
 extern int _commode;
 extern int _dowildcard;
 
-extern _CRTIMP void __cdecl _initterm(_PVFV *, _PVFV *);
-
 static int __cdecl check_managed_app (void);
 
 extern _PIFV __xi_a[];