title: Error when configuring gmp
body: <p>hope this is just a very simple question. Ok, here's what I've done: I wanted to install gmp under my Linux Ubuntu 11.10. I have both g++ and gcc on my system. So I downloaded the latest release from the gmp official site (gmp 5.0.2), extracted it and then, since I need the c++ gmp interface, I simply run:</p>
  
  <pre><code>./configure --enable-cxx
  </code></pre>
  
  <p>But it keeps working for a while and then prints out:</p>
  
  <pre><code>checking for suitable m4... configure: error: No usable m4 in $PATH or /usr/5bin (see config.log for reasons).
  </code></pre>
  
  <p>Did I do something wrong? Thank you very much!</p>
  
  <p>Matteo</p>