base: Move CaseInsensitiveCompare traits into the base namespace.

base: Move CaseInsensitiveCompare traits into the base namespace.

This should fix conflicts like:
2>d:\src\chromium_src2\src\base/string_util.h(480) : error C2904: 'CaseInsensitiveCompare' : name already used for a template in the current scope
2>        d:\src\chromium_src2\src\third_party\xulrunner-sdk\win\include\xpcom\nsStringAPI.h(1406) : see declaration of 'CaseInsensitiveCompare'

Reported-by: Jeff Timanus <twiz@google.com>;

BUG=None
TEST=trybots

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=64877

[tfarina, 2010-11-03 02:37:21]

+brett for review.

+jeff FYI.

[brettw, 2010-11-03 02:40:29]

LGTM