pull in base/stringprintf.h directly

Newer libbase has split this out of string_util.h, so we need to
explicitly include it now.

BUG=chromium-os:25872
TEST=`emerge-x86-alex libcros` works with old & new libbase

Change-Id: I73f83ba986d3d171f7e24c944f714d013614d25d
Reviewed-on: https://gerrit.chromium.org/gerrit/20200
Reviewed-by: Ryo Hashimoto <[email protected]>
Commit-Ready: Mike Frysinger <[email protected]>
Tested-by: Mike Frysinger <[email protected]>
1 file changed