An attempt to make this more Unix-friendly.

src/physfs_platforms.h

@@ -43,11 +43,11 @@
 #  define PHYSFS_PLATFORM_SOLARIS 1
 #  define PHYSFS_PLATFORM_UNIX 1
 #  define PHYSFS_PLATFORM_POSIX 1
-#elif defined(BSD)
+#elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__bsdi__) || defined(__DragonFly__)
 #  define PHYSFS_PLATFORM_BSD 1
 #  define PHYSFS_PLATFORM_UNIX 1
 #  define PHYSFS_PLATFORM_POSIX 1
-#elif defined(unix)
+#elif defined(unix) || defined(__unix__)
 #  define PHYSFS_PLATFORM_UNIX 1
 #  define PHYSFS_PLATFORM_POSIX 1
 #else