This is what happens right now:

$ sh ../configure --with-cacerts-file=non-existing-file
...

$ make
Building target 'default (exploded-image)' in configuration '/Users/cthalinger/jdk9/foo'
Creating support/modules_libs/java.base/libjsig.dylib from 1 file(s)
Compiling 8 files for BUILD_TOOLS_LANGTOOLS
Creating hotspot/variant-server/tools/adlc/adlc from 13 file(s)
Compiling 2 files for BUILD_JVMTI_TOOLS
make[3]: *** No rule to make target `non-existing-file', needed by `/Users/cthalinger/jdk9/foo/support/modules_libs/java.base/security/cacerts'. Stop.
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [java.base-copy-jdk] Error 2
make[2]: *** Waiting for unfinished jobs....

ERROR: Build failed for target 'default (exploded-image)' in configuration '/Users/cthalinger/jdk9/foo' (exit code 2)

No indication of failed target found.
Hint: Try searching the build log for '] Error'.
Hint: If caused by a warning, try configure --disable-warnings-as-errors.

make[1]: *** [main] Error 2
make: *** [default] Error 2