Small Request for review: 7005007 - Refine use of ALT_COMPILER_PATH to avoid conflict with JPRT usage

[David Holmes]

Simple fix to avoid conflicting use of ALT_COMPILER_PATH.

http://cr.openjdk.java.net/~dholmes/7005007/

Tested with JPRT linux builds and doing an internal cross-compile build.

Thanks,
David Holmes