RFR: JDK-8069261: Create make dependencies on make variable values

[Erik Joelsson]

Hello,

Please review this enhancement to the incremental build correctness. I 
have implemented a way to track make dependencies to make variable 
values, so that relevant changes to makefiles or configure will properly 
trigger rebuilds of affected targets. See bug description for more details.

Note that I've included new tests for these makefile features in the 
file test/make/TestMakeBase.gmk. These can be run with the target 
"test-make".

The macro MakeDir has been changed so that it no longer needs to be 
called with $(eval ).

I have chosen to define the new macros with = assignment instead of 
using "define", because they are meant to be called without $(eval ), 
which means they can only be one logical line. Since "define" is used to 
define multi line variables, it makes no sense to use it for these macros.

Bug: https://bugs.openjdk.java.net/browse/JDK-8069261
Webrev: http://cr.openjdk.java.net/~erikj/8069261/webrev.01/

/Erik