RFR (XS): 8199768 jdk/test/lib/compiler/CompilerUtils.java needs to provide more control over compilation

[David Holmes]

Unsure exactly who should review this ...

bug: https://bugs.openjdk.java.net/browse/JDK-8199768
webrev: http://cr.openjdk.java.net/~dholmes/8199768/webrev/

CompilerUtils.compile compiles all source files in a given directory 
tree into a specific directory. This is done by passing 
Integer.MAX_VALUE as the 'depth' argument to Files.find.

There are times when we** don't want to compile the entire tree into a 
single directory so it would be useful to be able to specify whether or 
not to recurse (depth = Integer.MAX_VALUE) or not (depth = 1).

** I need this for some tests I'm developing for Nestmates (JEP 181) and 
it will be simpler to fix this separately in mainline.

Testing:
   - check locally that test using CompilerUtils still pass.
   - mach5 jdk/hs tier1 and 2

Thanks,
David