hg: lanai/lanai: 8233034: configure needs to provide path to Xcode metal build tools

[philip.race at oracle.com]

Changeset: 87efedaa8192
Author:    ihse
Date:      2019-11-04 12:14 -0800
URL:       https://hg.openjdk.java.net/lanai/lanai/rev/87efedaa8192

8233034: configure needs to provide path to Xcode metal build tools
Reviewed-by: prr

! make/autoconf/spec.gmk.in
! make/autoconf/toolchain.m4
! make/lib/Awt2dLibraries.gmk
! make/lib/Lib-java.desktop.gmk