Correct local reference leaks

Correct local reference leaks

* src/android.c (android_build_string): Accept a list of local
references to destroy upon an allocation failure, facilitating
the proper deallocation of local references in such situations.
(android_browse_url): Revise for new calling convention.

* src/android.h (android_build_string): Update declaration
correspondingly.

* src/androidmenu.c (android_menu_show, android_dialog_show):
Revise for new calling convention.

* src/androidselect.c (android_notifications_notify_1): Supply
each successive local reference to android_build_string as
notification text is being encoded.

* src/androidvfs.c (android_saf_exception_check): Introduce
absent va_end.