RFR: JDK-8201267: Disable warnings for VS2017 to enable building

[Erik Joelsson]

We are rather close to being able to build the JDK using VS2017. There 
are still some warnings that need to be disabled (separate issues filed 
to fix them) and some other minor build tweaks that has surfaced now 
that Hotspot builds successfully.

With this patch, it should be possible to build using VS2017.

Notes on changes:

* In toolchain_windows.m4, the BASIC_FIXUP_PATH was redundant as all 
directories sent in here are already fixed. Calling it here messes up 
the filename of the dll, which in VS2017 is more than 8 chars.

* In NativeCompilation.gmk, this is unrelated but fixes incremental 
builds on Windows. Adlc.exe gets relinked every time otherwise.

* Reentrancy.c is a fix for JDK-8201215 suggested in bug comments there.

Bug: https://bugs.openjdk.java.net/browse/JDK-8201267
Webrev: http://cr.openjdk.java.net/~erikj/8201267/webrev.01/index.html

/Erik