Build error

[Jonathan Gibbons]

I'm trying to  build jigsaw-dev on Ubuntu.  I have a relatively clean 
forest (langtools changes only.)  I'm getting the following error 
building jdk;  does anyone recognize it?

>
> /w/jjg/work/jigsaw-merge/jigsaw/build/linux-amd64/tmp/java/java.lang/java/obj64/BootLoader.o: 
> In function `Java_org_openjdk_jigsaw_BootLoader_extendBootPath0':
> BootLoader.c:(.text+0x3c): undefined reference to 
> `JVM_ExtendBootClassPath'