Miscellaneous fixes for Android port

Miscellaneous fixes for Android port

* lisp/touch-screen.el (touch-screen-hold, touch-screen-drag):
Clear deactivate-mark if the mark is activated to prevent undue
deactivation after completion.

* lisp/wid-edit.el (widget-field, widget-single-line-field):
Insert specifications suitable for monochrome displays.

* src/androidfns.c (Fxw_display_color_p, Fx_display_grayscale_p):
Report color and/or grayscale properly.

* src/image.c (image_create_bitmap_from_file)
[HAVE_ANDROID]: If a file with no extension cannot be located,
append .xbm and retry.