title: How do I specify the compiler to use when cross-compiling rustc?
body: <p>When I compile <code>rustc</code>, there is a option in the configure script to specify other targets to the core libraries (<code>libcore</code>, <code>libstd</code>, etc), so for example:</p>
  
  <pre><code>./configure --target=x86_64-unknown-linux-gnu,i686-unknown-linux-gnu
  </code></pre>
  
  <p>will compile and install the <code>rustlibs</code> for both these architectures.</p>
  
  <p>My problem is that this command will use my default gcc to compile everything, (since my system is multilib, it will successfully compile to i686 too), but what I want is to use my toolchain compiler instead, so for example:</p>
  
  <p>I have 2 toolchains in my amd64 system: <code>i686-unknown-linux-gnu</code> and <code>arm-unknown-linux-gnueabi</code>.</p>
  
  <p>When I run configure with these parameters:</p>
  
  <pre><code>./configure --target=x86_64-unknown-linux-gnu,i686-unknown-linux-gnu,arm-unknown-linux-gnueabi
  </code></pre>
  
  <p>When compiling the <code>rustlibs</code>, I want the script to use x86_64-unknown-linux-gnu-<strong>gcc</strong> for <code>x86_64</code>, and i686-unknown-linux-gnu-<strong>gcc</strong> for <code>i686</code> and arm-unknown-linux-gnueabi-<strong>gcc</strong> for <code>arm</code>.</p>
  
  <p>That way the <code>rustlib</code> will be compiled using the <code>glibc</code> and other libraries from the toolchain and not the default from my system. Is that possible?</p>