cannot build jigsaw: undefined reference to `JVM_ExtendBootClassPath'

[Jonathan Gibbons]

Anyone seen this?  This is from a fresh copy of the jigsaw forest.

-- Jon

/mnt/w/jjg/work/jigsaw/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'
collect2: ld returned 1 exit status
make[4]: *** 
[/mnt/w/jjg/work/jigsaw/jigsaw/build/linux-amd64/lib/amd64/libjava.so] 
Error 1
make[4]: Leaving directory 
`/mnt/w/jjg/work/jigsaw/jigsaw/jdk/make/java/java'
make[3]: *** [all] Error 1
make[3]: Leaving directory `/mnt/w/jjg/work/jigsaw/jigsaw/jdk/make/java'
make[2]: *** [all] Error 1
make[2]: Leaving directory `/mnt/w/jjg/work/jigsaw/jigsaw/jdk/make'
make[1]: *** [jdk-build] Error 2
make[1]: Leaving directory `/mnt/w/jjg/work/jigsaw/jigsaw'
make: *** [build_product_image] Error 2