c-common.c (c_common_truthvalue_conversion): Warn only for signed integer shift ops in boolean context.

2016-10-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-common.c (c_common_truthvalue_conversion): Warn only for signed
        integer shift ops in boolean context.

testsuite:
2016-10-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-c++-common/Wint-in-bool-context-2.c: New test.

From-SVN: r241354