in my mac OSX 10.6 32 bit, I can install mysql2 gem quite easily, but not in mini mac 10.6 64bit server.
I have installed MySQL 5.5.11 in troublesome server, while i
I did a bundle install on a redmine repo and got the same error message :
mysql.h is missing. please check your installation of mysql and try again.
Running Fedora 16 64 bits, all I did was install mysql-devel (development package) from the distro rpm and the problem was solved!
So I think you could just
yum install mysql-devel
or apt-get the missing devel package.