8004229: build-infra: Umbrella for switch of default "make" to new makefiles

Reviewed-by: erikj, tbell

Makefile

@@ -26,6 +26,11 @@
 # If NEWBUILD is defined, use the new build-infra Makefiles and configure.
 #     See NewMakefile.gmk for more information.
 
+# If not specified, select what the default build is
+ifndef NEWBUILD
+  NEWBUILD=true
+endif
+
 ifeq ($(NEWBUILD),true)
 
   # The new top level Makefile

make/jprt.properties

@@ -28,6 +28,9 @@
 # Locked down to jdk8
 jprt.tools.default.release=jdk8
 
+# Unix toolkit to use for building on windows
+jprt.windows.jdk8.build.unix.toolkit=cygwin
+
 # The different build flavors we want, we override here so we just get these 2
 jprt.build.flavors=product,fastdebug