archive-tar: fix a sparse 'constant too large' warning

archive-tar: fix a sparse 'constant too large' warning

Commit dddbad728c ("timestamp_t: a new data type for timestamps",
26-04-2017) introduced a new typedef 'timestamp_t', as a synonym for an
unsigned long, which was used at the time to represent timestamps in
git. A later commit 28f4aee3fb ("use uintmax_t for timestamps",
26-04-2017) changed the typedef to use an 'uintmax_t' for the timestamp
representation type.

When building on a 32-bit Linux system, sparse complains that a constant
(USTAR_MAX_MTIME) used to detect a 'far-future mtime' timestamp, is too
large; 'warning: constant 077777777777UL is so big it is unsigned long
long' on lines 335 and 338 of archive-tar.c. Note that both gcc and
clang only issue a warning if this constant is used in a context that
requires an 'unsigned long' (rather than an uintmax_t). (Since TIME_MAX
is no longer equal to 0xFFFFFFFF, even on a 32-bit system, the macro
USTAR_MAX_MTIME is set to 077777777777UL, which cannot be represented as
an 'unsigned long' constant).

In order to suppress the warning, change the definition of the macro
constant USTAR_MAX_MTIME to use an 'ULL' type suffix.

In a similar vein, on systems which use a 64-bit representation of the
'unsigned long' type, the USTAR_MAX_SIZE constant macro is defined with
the value 077777777777ULL. Although this does not cause any warning
messages to be issued, it would be more appropriate for this constant
to use an 'UL' type suffix rather than 'ULL'.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>