PHP5 and 64 bits
When compiling PHP on a 64 bit system don’t forget to add “–with-libdir=/lib64″ to the configure statement. A typical configure statement would be:
./configure –with-apxs2=/usr/local/apache2/bin/apxs –with-mysql –with-libdir=/lib64
If you forget “–with-libdir”, make will fail in the mysql section with the error:
configure: error: Cannot find libmysqlclient under /usr.
Note that the MySQL client library is not bundled anymore!
Source: http://www.blackbeagle.com/2006/10/06/compiling-php-on-a-64-bit-system/