SunOS/ODS compile warnings

[ebraminio]

Not sure but I guess some of warnings ODS gives are interesting to have a look. On https://circleci.com/gh/harfbuzz/harfbuzz/4166 the "make -Cbuild", three distinct warning:

"/root/project/src/hb-icu.cc", line 234: Warning: Likely out-of-bound read: *(decomposed[-1]) in function hb_icu_unicode_decompose 

	prototype: pointer to unsigned int : "/root/project/src/hb-ot-tag.h", line 43
	argument : pointer to enum  {_HB_SCRIPT_MAX_VALUE_SIGNED(2147483647),

"/root/project/src/hb-common.h", line 328: warning: integer overflow detected: op "<<"
"/root/project/src/hb-common.h", line 328: warning: enumerator value overflows INT_MAX (2147483647) ...

Some can be ignored I guess,

"/root/project/src/hb-ot-layout-gsubgpos-private.hh", line 336: Warning: c hides OT::hb_apply_context_t::skipping_iterator_t::c.
"/root/project/src/hb-ot-layout-gsubgpos-private.hh", line 414: Warning: lookup_index hides OT::hb_apply_context_t::lookup_index.

"/root/project/src/hb-ot-map.cc", line 83: Warning: face hides hb_ot_map_builder_t::face.

and CC: Warning: GCC option -fno-rtti ignored which is fixed on #710

[behdad]

Thanks. Fixed all but the first two, which are harmless / hard to silence.