Changes to the unix VFS that allegedly enable it to build of Fuchsia.

We have no way of testing this.

FossilOrigin-Name: be21a6416d47ff7db995006a0422b745044d9b8bb5bad3c53342aa6e2e524771

src/os_unix.c

@@ -7822,6 +7822,9 @@ int sqlite3_os_init(void){
     UNIXVFS("unix",          autolockIoFinder ),
 #elif OS_VXWORKS
     UNIXVFS("unix",          vxworksIoFinder ),
+#elif __Fuchsia__
+    /* We are told that Fuchsia only supports dot-file locking */
+    UNIXVFS("unix",          dotlockIoFinder ),
 #else
     UNIXVFS("unix",          posixIoFinder ),
 #endif