Upgrade formula: MySQL Cluster 7.2.8.

Update the formula to build the latest stable release of MySQL Cluster.

Model the code upon the MySQL formula (remove unnecessary dependencies
and patches, use conflicts_with, etc...).

Slightly simplify caveats.

Tested in the following environment:

HOMEBREW_VERSION: 0.9.3
HEAD: 59090919df8257d5f8eab8a2cb26bfd2eda3e32d
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
CPU: quad-core 64-bit sandybridge
OS X: 10.8.2-x86_64
Xcode: 4.5.2
CLT: 4.5.0.0.1.1249367152
LLVM-GCC: build 2336
Clang: 4.1 build 421
X11: 2.7.4 => /opt/X11
System Ruby: 1.8.7-358
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /Users/lifepillar/.rbenv/shims/ruby

Built without additional options and with all the options turned on.

It seems that compiling with clang has still an issue, but gcc and llvm are fine.