[!USE_CRT_DLL]: Don't define _heap_init and _heap_term

unless we are linking with a static CRT.
(RVA_TO_PTR): Cast result to unsigned char*.

src/w32heap.c

@@ -30,7 +30,7 @@ Boston, MA 02111-1307, USA.
 #include "lisp.h"  /* for VALMASK */
 
 #undef RVA_TO_PTR
-#define RVA_TO_PTR(rva) ((DWORD)(rva) + (DWORD)GetModuleHandle (NULL))
+#define RVA_TO_PTR(rva) ((unsigned char *)((DWORD)(rva) + (DWORD)GetModuleHandle (NULL)))
 
 /* This gives us the page size and the size of the allocation unit on NT.  */
 SYSTEM_INFO sysinfo_cache;
@@ -275,7 +275,7 @@ round_heap (unsigned long align)
     sbrk (need_to_alloc);
 }
 
-#if (_MSC_VER >= 1000)
+#if (_MSC_VER >= 1000 && !defined(USE_CRT_DLL))
 
 /* MSVC 4.2 invokes these functions from mainCRTStartup to initialize
    a heap via HeapCreate.  They are normally defined by the runtime,