Review Request: 8008295: build-infra: Cleanup in Import.gmk

[Erik Joelsson]

Cleaning up in jdk/makefiles/Import.gmk. Removing two copies of the 
install-file macro which is already defined in 
common/makefiles/MakeBase.gmk.

http://cr.openjdk.java.net/~erikj/8008295/webrev.jdk.01/
/Erik