unistd: port to iOS

Problem reported by André Klitzing in:
http://lists.gnu.org/archive/html/bug-gnulib/2014-11/msg00013.html
* lib/unistd.in.h (environ): Do not include crt_externs.h on iOS.
fts: port to C89

Problem reported for MSVC 16 by Gisle Vanem in:
http://lists.gnu.org/archive/html/bug-gnulib/2014-11/msg00027.html
* lib/fts.c (fts_build): Avoid declaration before statement.
fcntl-h-tests: port to PA-RISC GNU/Linux

* tests/test-fcntl-h.c (main): Check O_SYNC is different from O_DSYNC.
gen-uni-tables: cosmetic improvements

* lib/gen-uni-tables.c: Escape newlines in the Emacs file local
variables specification.
(is_outdigit): Remove unused function.
gen-uni-tables: utilize 'assert'

* lib/gen-uni-tables.c: Include <assert.h>.
(output_category, output_combclass, output_decimal_digit_test)
(output_decimal_digit, output_digit_test, output_digit)
(output_numeric, get_mirror_value, fill_properties)
(fill_property30, is_property_alphabetic)
(is_property_default_ignorable_code_point)
(is_property_uppercase, is_property_lowercase)
(is_property_cased, is_property_case_ignorable)
(is_property_changes_when_lowercased, is_property_iso_control)
(is_property_math, fill_arabicshaping, output_joining_group)
(fill_scripts, fill_blocks, output_lbp, fill_org_wbp)
(output_wbp, fill_org_gbp, get_decomposition)
(output_decomposition, fill_composition_exclusions)
(debug_output_composition_tables, output_composition_tables)
(redistribute_casefolding_rules, output_casing_rules): Use
'assert (EXPR);' instead of 'if (!EXPR) abort ();' for better error
reporting.
gen-uni-tables: check out-of-range values added to 3-level tables

* lib/gen-uni-tables.c (output_category, output_bidi_category)
(output_joining_type, output_ident_category): Check out-of-range
values added to 3-level tables.
gen-uni-tables: untabify

* lib/gen-uni-tables.c: Untabify.
extern-inline: update commentary about GCC bugs

* m4/extern-inline.m4: Add another GCC bug number to comments.
update from texinfo