[view] Crash with --glyphs if given more than one glyph

[khaledhosny]

The following works:

$ hb-shape Amiri-Regular.ttf a | hb-view --glyphs Amiri-Regular.ttf

and this also works:

$ hb-shape Amiri-Regular.ttf ا | hb-view --glyphs Amiri-Regular.ttf

But this crashes:

$ hb-shape Amiri-Regular.ttf ab | hb-view --glyphs Amiri-Regular.ttf
Segmentation fault: 11

And this asserts:

$ hb-shape Amiri-Regular.ttf اب | hb-view --glyphs Amiri-Regular.ttf
Assertion failed: (hb_glyph[i].cluster > hb_glyph[i-1].cluster), function hb_cairo_glyphs_from_buffer, file hb-cairo.cc, line 897.
Abort trap: 6

[khaledhosny]

Adding --no-clusters to hb-shape fixes the crash and the assert.