[ecj] gjar is installed, but we don't use it in the build

[Andrew Haley]

Enough said:

 $ time /bin/sh /home/aph/gcc/gcj-eclipse-premerge/gcj-eclipse-merge-branch/obj-x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/libjava/scripts/jar -cfM /home/aph/gcc/gcj-eclipse-premerge/gcj-eclipse-merge-branch/obj-x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/libjava/libgcj-4.3.0.jar gnu java javax org sun

real    2m29.540s
user    0m31.106s
sys     1m48.567s

 $ time /usr/local/gcj/bin/gjar  -cfM /home/aph/gcc/gcj-eclipse-premerge/gcj-eclipse-merge-branch/obj-x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/libjava/libgcj-4.3.0.jar gnu java javax org sun
 
real    0m9.170s
user    0m8.353s
sys     0m0.380s

Weirdly, overriding JAR from the command line does not seem to work:

 $ make JAR=/usr/local/gcj/bin/gjar
...
make[1]: Entering directory `/home/aph/gcc/gcj-eclipse-premerge/gcj-eclipse-merge-branch/obj-x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/libjava'
here=`pwd`; cd ../../../libjava/classpath/lib; /home/aph/gcc/gcj-eclipse-premerge/gcj-eclipse-merge-branch/obj-x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/libjava/scripts/jar -cfM \
    $here/libgcj-4.3.0.jar gnu java javax org sun

JAR is set correctly at the start of the make, but something goes
wrong later.  Something to do with recursive make, perhaps?

IMO this should be a merge blocker.

Andrew.