RFR (XS) 8218859: jdk.tools.jaotc.collect.ClassSearch:makeList() uses ":" instead of File.pathSeparator

[Ekaterina Pavlova]

Hi,

jdk.tools.jaotc.collect.ClassSearch:makeList() uses ":" instead of File.pathSeparator and as result
returns improper list for Windows paths. Please review this simple fix.

Also created new compiler/aot/cli/jaotc/CompileAbsoluteDirectoryTest.java regression test to cover this.

     jbs: https://bugs.openjdk.java.net/browse/JDK-8218859
  webrev: http://cr.openjdk.java.net/~epavlova//8218859/webrev.00/index.html
testing: tested by running compiler/aot tests on windows and linux platforms.

thanks,
-katya