Bug#924339: javahelper regressed building -doc packages

[Matthias Klose]

looks like jh_build doesn't recognize --no-javadoc. -N correctly skips the doc
build.

But then android-platform-build/jh_build fails with

jh_build --javacopts="-source 7" -N --main=com.android.signapk.SignApk
signapk.jar tools/signapk/
warning: [options] bootstrap class path not set in conjunction with -source 7
1 warning
java.nio.file.NoSuchFileException: /tmp/signapk.jar4641574884122648833.jar ->
/home/packages/tmp/at/android-platform-build-8.1.0+r23/signapk.jar/signapk.jar
        at
java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:92)
        at
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
        at java.base/sun.nio.fs.UnixCopyFile.move(UnixCopyFile.java:478)
        at
java.base/sun.nio.fs.UnixFileSystemProvider.move(UnixFileSystemProvider.java:263)
        at java.base/java.nio.file.Files.move(Files.java:1421)
        at jdk.jartool/sun.tools.jar.Main.validateAndClose(Main.java:466)
        at jdk.jartool/sun.tools.jar.Main.run(Main.java:349)
        at jdk.jartool/sun.tools.jar.Main.main(Main.java:1681)
jh_build: cd debian/_jh_build.signapk && /usr/lib/jvm/default-java/bin/jar cfm
"/home/packages/tmp/at/android-platform-build-8.1.0+r23/signapk.jar/signapk.jar"
../_jh_manifest.signapk * returned exit code 1
make[1]: *** [debian/rules:26: signapk.jar] Error 2