Adapt to switch to libc++ for Windows

Bug: http://b/91353691

- libcxx has ETXTBSY for Windows
- adb/sysdeps/memory.h is no longer needed

Test: Build and test Windows binaries under Wine.

Change-Id: I9c27087d46c49cb25b391c4adae8d9e24724784d
diff --git a/sysdeps_win32.cpp b/sysdeps_win32.cpp
index 026dd1c..38cdb57 100644
--- a/sysdeps_win32.cpp
+++ b/sysdeps_win32.cpp
@@ -95,6 +95,10 @@
     _fh_socket_writev,
 };
 
+#if defined(assert)
+#undef assert
+#endif
+
 #define assert(cond)                                                                       \
     do {                                                                                   \
         if (!(cond)) fatal("assertion failed '%s' on %s:%d\n", #cond, __FILE__, __LINE__); \