Save 4 bytes per CFX_ByteString where size_t smaller than long.

Save 4 bytes per CFX_ByteString where intptr_t smaller than long.

Also prevent theoretical roll-over where long smaller than intptr_t.
See bug for discussion.

BUG=pdfium:149
R=thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/34989e42d94f0b4f982117032f29ae3cce1e1a39

[Tom Sepez, 2015-05-01 22:28:18]

tsepez@chromium.org changed reviewers:
+ thestig@chromium.org

[Tom Sepez, 2015-05-01 22:28:19]

Lei, for review.  Even better.

[Lei Zhang, 2015-05-01 22:53:47]

lgtm

Did you mean to say intptr_t instead of size_t?

[Tom Sepez, 2015-05-01 23:04:35]

Committed patchset #2 (id:20001) manually as
34989e42d94f0b4f982117032f29ae3cce1e1a39 (presubmit successful).

[dreamfly912, 2015-05-08 03:55:36]

On 2015/05/01 22:28:19, Tom Sepez wrote:
> Lei, for review.  Even better.

Hi Tom, why intptr_t is smaller than long?

[dreamfly912, 2015-05-08 03:59:47]

On 2015/05/08 03:55:36, dreamfly912 wrote:
> On 2015/05/01 22:28:19, Tom Sepez wrote:
> > Lei, for review.  Even better.
> 
> Hi Tom, why intptr_t is smaller than long?

afaik, on 32bit platform, both intptr_t and long are 32bit; on 64bit Linux(LP64)
platform, both intptr_t and long are 64bit; on 64bit Windows(LP64) platform,
intptr_t is 64bit and long is 32bit;
Thanks :)

[Tom Sepez, 2015-05-08 17:04:23]

On 2015/05/08 03:59:47, dreamfly912 wrote:
> On 2015/05/08 03:55:36, dreamfly912 wrote:
> > On 2015/05/01 22:28:19, Tom Sepez wrote:
> > > Lei, for review.  Even better.
> > 
> > Hi Tom, why intptr_t is smaller than long?
> 
> afaik, on 32bit platform, both intptr_t and long are 32bit; on 64bit
Linux(LP64)
> platform, both intptr_t and long are 64bit; on 64bit Windows(LP64) platform,
> intptr_t is 64bit and long is 32bit;
> Thanks :)

Nothing in the standards say that it has to be that way.  What you're talking
about are implementation details of current platforms, which may happily work
out or may not.