title: libmpfr.so.4 dependency with --disable-shared
body: <p>everyone!
  I have the same result 
  **</p>
  
  <blockquote>
    <p>error while loading shared libraries: libmpfr.so.4: cannot open shared
    object file: No such file or directory</p>
  </blockquote>
  
  <p>but under another configure :</p>
  
  <pre><code>../gcc.s/configure      \
  --target=$LFS_TGT       \
  --prefix=/tools     \
  --with-sysroot=$LFS     \
  --with-newlib       \
  --without-headers       \
  --with-local-prefix=/tools  \
  --with-native-system-header-dir=/tools/include  \
  --disable-nls       \
  --disable-shared        \
  --disable-multlib       \
  --disable-decimal-float \
  --disable-threads       \
  --disable-libmudflap    \
  --disable-libssp        \
  --disable-libgomp       \
  --disable-libquadmath   \
  --enable-language=c     
  </code></pre>
  
  <p>having gmp, mpc, mpfr present in the GCC source tree</p>
  
  <p>My question is 
  how did it turn out that <code>--disable-shared</code>
  enable to link cc1 against <code>libmpfr.so.4</code> insteed static <code>libmpfr.a</code>
  which is present in gcc build results:</p>
  
  <pre><code>gcc.b/mpfr/src/.libs/libmpfr.a
  </code></pre>