Stop linking with -base:0x8000000 on Windows

On Windows, jvm.dll is linked with -base:0x8000000. VS2017 version 15.5 is generating a linker warning with regards to -base's specification.

LINK : warning LNK4281: undesirable base address 0x8000000 for x64 image; set base address above 4GB for best ASLR optimization

According to:
https://developercommunity.visualstudio.com/content/problem/160970/upgrading-from-154-to-155-throw-lnk4281-warning.html there is potential for missed ASLR optimizations.

Investigate why historically -base was specified as a linker option on Windows and remove if unnecessary.