win32: early load -luv on win32

on win32 dynamic relocation of system dlls is tricky and unstable, when loading
aio.dll and sometimes buffile.dll it failed to relocate user32.dll.
also add the length arg for a potion_mmap fail (win32 only)

config.mak

@@ -190,6 +190,7 @@ ifeq ($(shell tools/config.sh "${CC}" mingw),1)
 	LOADEXT = .dll
 	INCS += -I${PWD}/tools/dlfcn-win32/include
 	LIBPTH += -L${PWD}/tools/dlfcn-win32/lib
+	LIBS += -Llib -luv
     ifneq (,$(findstring i386-mingw32-gcc,${CC}))
 	LIBS += -lws2_32 -lpsapi
     else
@@ -221,6 +222,7 @@ ifeq ($(shell tools/config.sh "${CC}" cygwin),1)
 	CYGWIN = 1
 	LDFLAGS += -Wl,--major-image-version,0,--minor-image-version,1
 	LDDLLFLAGS = -shared
+	LIBS += -Llib -luv
 	LOADEXT = .dll
 	EXE  = .exe
 	DLL  = .dll

core/contrib.c

@@ -53,7 +53,7 @@ void *potion_mmap(size_t length, const char exec)
   void *mem = VirtualAlloc(NULL, length, MEM_COMMIT,
     exec ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE);
   if (mem == NULL)
-    fprintf(stderr, "** potion_mmap failed");
+    fprintf(stderr, "** potion_mmap %ld failed", length);
   return mem;
 }