Trying to compile gem mysql on MacOSX, what can be wrong?

Compiling gem mysql on MacOSX fail!

$ ls -al /usr/local/
total 8
drwxr-xr-x   6 root  wheel  204 29 Out 15:12 .
drwxr-xr-x@ 14 root  wheel  476  1 Nov 13:45 ..
drwxr-xr-x   3 root  wheel  102 29 Out 15:12 bin
drwxr-xr-x   8 root  wheel  272 29 Out 12:59 git
lrwxr-xr-x   1 root  wheel   24 29 Out 13:02 mysql -> mysql-5.1.51-osx10.6-x86
drwxr-xr-x  17 root  wheel  578 13 Set 13:44 mysql-5.1.51-osx10.6-x86

$ env ARCHFLAGS="-arch i386" gem install mysql --   --with-mysql-dir=/usr/local/mysql/ --with-mysql-lib=/usr/local/mysql/lib   --with-mysql-include=/usr/local/mysql/include

Building native extensions.  This could take a while...
ERROR:  Error installing mysql:
	ERROR: Failed to build gem native extension.

/Users/ruiandrada/.rvm/rubies/ruby-1.8.7-p302/bin/ruby extconf.rb --with-mysql-dir=/usr/local/mysql/ --with-mysql-lib=/usr/local/mysql/lib --with-mysql-include=/usr/local/mysql/include
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... yes
checking for mysql_query() in -lmysqlclient... no
*** 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=/Users/ruiandrada/.rvm/rubies/ruby-1.8.7-p302/bin/ruby
	--with-mysql-config
	--without-mysql-config
	--with-mysql-dir
	--with-mysql-include=${mysql-dir}/include
	--with-mysql-lib=${mysql-dir}/lib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mlib
	--without-mlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-zlib
	--without-zlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-socketlib
	--without-socketlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-nsllib
	--without-nsllib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mygcclib
	--without-mygcclib
	--with-mysqlclientlib
	--without-mysqlclientlib


Gem files will remain installed in /Users/ruiandrada/.rvm/gems/ruby-1.8.7-p302@global/gems/mysql-2.8.1 for inspection.
Results logged to /Users/ruiandrada/.rvm/gems/ruby-1.8.7-p302@global/gems/mysql-2.8.1/ext/mysql_api/gem_make.out