Update build-osx.md

The homebrew instructions were outdated - berkeley-db4 hasn't worked for months, based on the questions I'm seeing on Google/SO.  So I added a section explaining how to install berkeley-db4 using homebrew and move on with your life.  Thanks for the rest of the documentation!

doc/build-osx.md

@@ -69,7 +69,7 @@ Instructions: Homebrew
 
 #### Install dependencies using Homebrew
 
-        brew install autoconf automake libtool berkeley-db4 boost miniupnpc openssl pkg-config protobuf qt
+        brew install autoconf automake libtool boost miniupnpc openssl pkg-config protobuf qt
 
 Note: After you have installed the dependencies, you should check that the Homebrew installed version of OpenSSL is the one available for compilation. You can check this by typing
 
@@ -85,6 +85,29 @@ Rerunning "openssl version" should now return the correct version. If it
 doesn't, make sure `/usr/local/bin` comes before `/usr/bin` in your
 PATH. 
 
+#### Installing berkeley-db4 using Homebrew
+
+The homebrew package for berkeley-db4 has been broken for some time.  It will install without Java though.
+
+Running this command takes you into brew's interactive mode, which allows you to configure, make, and install by hand:
+```
+$ brew install https://raw.github.com/mxcl/homebrew/master/Library/Formula/berkeley-db4.rb -–without-java 
+```
+
+These rest of these commands are run inside brew interactive mode:
+```
+/private/tmp/berkeley-db4-UGpd0O/db-4.8.30 $ cd ..
+/private/tmp/berkeley-db4-UGpd0O $ db-4.8.30/dist/configure --prefix=/usr/local/Cellar/berkeley-db4/4.8.30 --mandir=/usr/local/Cellar/berkeley-db4/4.8.30/share/man --enable-cxx
+/private/tmp/berkeley-db4-UGpd0O $ make
+/private/tmp/berkeley-db4-UGpd0O $ make install
+/private/tmp/berkeley-db4-UGpd0O $ exit
+```
+
+After exiting, you'll get a warning that the install is keg-only, which means it wasn't symlinked to `/usr/local`.  You don't need it to link it to build bitcoin, but if you want to, here's how:
+
+    $ brew --force link berkeley-db4
+
+
 ### Building `bitcoind`
 
 1. Clone the github tree to get the source code and go into the directory.