Fix warning with VS2017 in jdk.pack

When compiling jdk.pack with VS2017, the following warning is triggered. I will disable the warning from the makefile, but the component team needs to evaluate if this should be fixed.

c:\erik\jdk\open\src\jdk.pack\share\native\common-unpack\utils.h(36): warning C4005: 'OVERFLOW': macro redefinition
c:\progra~2\window~3\10\include\100162~1.0\ucrt\corecrt_math.h(966): note: see previous definition of 'OVERFLOW'

Note that this file is picked up by both pack200 and libunpack.