Implement dots and dashes on Android

* java/org/gnu/emacs/EmacsDrawLine.java (EmacsDrawLine)
(measureLine, polyDashPattern): New function.
(perform): Delegate to polyDashPattern if the line style is not
LineSolid.  Also simplify now that anti-aliasing need no longer
be taken into account.

* java/org/gnu/emacs/EmacsDrawRectangle.java (perform): Mention
omission in commentary.

* java/org/gnu/emacs/EmacsGC.java (EmacsGC): Disable
anti-aliasing in default paint object.
<line_style, line>: New fields.
(markDirty): Apply stroke width.

* src/android.c (android_init_emacs_gc_class): Initialize new
fields.
(android_create_gc, android_free_gc, android_change_gc)
(android_set_dashes, android_get_gc_values):

* src/androidgui.h (enum android_line_style)
(enum android_gc_value_mask, struct android_gc): Introduce line
style, width, dash offset and dash GC attributes.

* src/androidterm.c (android_draw_dash, android_fill_underline)
(android_draw_glyph_string): Port from X.

* src/xterm.c (x_draw_dash): Delete redundant code.

java/org/gnu/emacs/EmacsDrawRectangle.java

@@ -52,6 +52,9 @@ public final class EmacsDrawRectangle
     paint = gc.gcPaint;
     paint.setStyle (Paint.Style.STROKE);
 
+    /* This graphics request, in contrast to X, does not presently
+       respect the GC's line style.  */
+
     if (gc.clip_mask == null)
       /* Use canvas.drawRect with a RectF.  That seems to reliably
 	 get PostScript behavior.  */