This is due to jvm.cfg being regenerated only for 32-bit VMs, so the jlink fails with:

Building targets 'clean-hotspot images' in configuration 'linux-x86_64-normal-minimal-release'
Cleaning hotspot build artifacts ... done
Compiling 2 files for BUILD_JVMTI_TOOLS
Updating support/modules_libs/java.base/minimal/libjvm.so due to 470 file(s)
Creating hotspot/variant-minimal/libjvm/gtest/libjvm.so from 76 file(s)
Creating hotspot/variant-minimal/libjvm/gtest/gtestLauncher from 1 file(s)
Error: missing `server' JVM at `/home/shade/trunks/jdk-jdk/build/linux-x86_64-normal-minimal-release/jdk/lib/server/libjvm.so'.
Please install or use the JRE or JDK that contains these missing components.

While Minimal VM is targeted to 32-bit only, it makes some sense to allow it to build cleanly on 64-bit too.