use $(MAKE) in the makefile, so FreeBSD will use the right make tool (gmake)

[robbak]

After the leveldb import, src/makefile.unix has the 'make' command for leveldb hard coded. When a build is run on FreeBSD, it uses the system make, which uses different syntaxes.
Using the macro $(MAKE) will cause it to run gmake, and the build will work.

[Diapolo]

@robbak You should not merge upstream changes but rebase your pull onto current master. The way this pull is now it won't be accepted I think.

• git checkout "local branch"
• git fetch upstream
• git rebase upstream
• git push origin "local branch" -f

[gavinandresen]

Needs to be rebased into one commit, and the same change should be made to the other OS's Makefiles.

[robbak]

I've messed up my clone, so I'll do it again, the right way.
Thanks.