I am trying to install the `mysql2` gem via the Bundler, but it keeps dying with the following error:

```
** executing command
/home/cc_rails/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/rubygems/installer.rb:483:in 'rescue in block in build_extensions': 
ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

/home/cc_rails/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb --with-mysql-config=/usr/bin/mysql_config
checking for rb_thread_blocking_region()... yes
checking for mysql.h... no
checking for mysql/mysql.h... no

-----
mysql.h is missing.  please check your installation of mysql and try again.
-----

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/home/cc_rails/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
--with-mysql-config
Gem files will remain installed for inspection.

```

Most things I found via Googling recommended passing the `--with-mysql-config` parameter to fix it. So, based on:

```
$ which mysql_config
/usr/bin/mysql_config

```

I added the following to the Bundler's config:

```
$ bundle config build.mysql2 --with-mysql-config='/usr/bin/mysql_config'

```

However, still no luck -- same crash as above.

Since it's dying with the error `mysql.h is missing`, I checked for that, and it's allegedly around, just can't be found by the Bundler.

```
$ find / -name mysql.h
/usr/include/mysql5/mysql/mysql.h

```

Any thoughts?