[windows] Properly use dllimport / dllexport.
Update the headers, so we can change the dllexports to dllimport when
defining SANITIZER_IMPORT_INTERFACE.
// Only use SANITIZER_*ATTRIBUTE* before the function return type!
#if SANITIZER_WINDOWS
+#if SANITIZER_IMPORT_INTERFACE
+# define SANITIZER_INTERFACE_ATTRIBUTE __declspec(dllimport)
+#else
# define SANITIZER_INTERFACE_ATTRIBUTE __declspec(dllexport)
+#endif
# define SANITIZER_WEAK_ATTRIBUTE
#elif SANITIZER_GO
# define SANITIZER_INTERFACE_ATTRIBUTE
