Some client libraries cannot be built with GCC 6

http://mail.openjdk.java.net/pipermail/jdk9-dev/2016-June/004494.html

Some client libraries could not be built with misleading-indentation
and shift-negative-value warining (error) on GCC 6.1.1 .

So I think we have to fix new warnings.

However, some libraries (LCMS, JPEG library, and fdlibm) are imported
from another open source project. So we should avoid compile error
with suppressing them.