Review Request: 8003819: build-infra: backslashes at end of LIB and INCLUDE in spec.gmk

[Erik Joelsson]

This fixes a problem where the LIB and INCLUDE variables end up with a \ 
at the end in spec.gmk. These variables are set in vcvars.bat and 
configure extracts them to spec.gmk. Normally they do not end with a 
backslash, but if these variables are already set before running 
configure, they might. One case where this happens is if Visual Studio 
2003 is installed on the system.

http://cr.openjdk.java.net/~erikj/8003819/webrev.01/

/Erik