v3/ec: enable full version of c++ standard library

The newest version of pigweed requires the chrono and algorithm
header files that are available only in full version of c++ std
library. This commit enables it allowing to compile successfully with
newest version of pigweed.
The memory footprints are as specified:

Before enabling the full library:
Memory region         Used Size  Region Size  %age Used
           FLASH:      193868 B         2 MB      9.24%
             RAM:       34340 B       512 KB      6.55%

After enabling:
Memory region         Used Size  Region Size  %age Used
           FLASH:      189776 B         2 MB      9.05%
             RAM:       42580 B       512 KB      8.12%

BUG=b:319924603
TEST=repo sync and compile the EC using recent version of pigweed

Change-Id: I1aa92e4fb7469ff6d410754b21791af43d90c330
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/5213306
Reviewed-by: Alexandru Stan <amstan@chromium.org>
Tested-by: Michał Barnaś <barnas@google.com>
Commit-Queue: Michał Barnaś <barnas@google.com>
1 file changed