title: Cannot properly link ZSTD library when building GCC 10
body: <p>I'm trying to build GCC 10 from source in Ubuntu 20.04, and I have built the other dependencies. Below is the the flags I have set to configure the make files:</p>
  <pre><code>$PWD/../gcc/configure \
  --with-gmp=/tmp/gcc \
  --with-mpfr=/tmp/gcc \
  --with-mpc=/tmp/gcc \
  --with-zstd=/../zstd
  </code></pre>
  <p>where gmp, mpfr, and mpc are in /tmp/gcc. I cannot build zstd in /tmp/gcc as there is no configure file for it. When I tried to run the command <code>make -j8</code>, this is the output I get:</p>
  <pre><code>$PWD/../gcc/gcc/lto-compress.c:120: error: undefined reference to 'ZSTD_maxCLevel'
  $PWD/../gcc/gcc/lto-compress.c:121: error: undefined reference to 'ZSTD_maxCLevel'
  $PWD/../gcc/gcc/lto-compress.c:135: error: undefined reference to 'ZSTD_compressBound'
  $PWD/../gcc/gcc/lto-compress.c:138: error: undefined reference to 'ZSTD_compress'
  $PWD/../gcc/gcc/lto-compress.c:141: error: undefined reference to 'ZSTD_isError'
  $PWD/../gcc/gcc/lto-compress.c:142: error: undefined reference to 'ZSTD_getErrorName'
  $PWD/../gcc/gcc/lto-compress.c:161: error: undefined reference to 'ZSTD_getFrameContentSize'
  $PWD/../gcc/gcc/lto-compress.c:168: error: undefined reference to 'ZSTD_decompress'
  $PWD/../gcc/gcc/lto-compress.c:170: error: undefined reference to 'ZSTD_isError'
  $PWD/../gcc/gcc/lto-compress.c:171: error: undefined reference to 'ZSTD_getErrorName'
  collect2: error: ld returned 1 exit status
  </code></pre>
  <p>I have already tried too obtain ZSTD from <code>sudo apt-get install zstd</code> and updated my PATH, but nothing has happened. What do I need to do to get this working?</p>