Remove the mpc and mpfr from gcc buildout and headless-chromium buildout

The mpc and mpfr component already in the component/binutils.cfg. Remove the duplicate ones.

Update: the test passed. @rafael 

/reviewed-on !163

component/gcc/buildout.cfg

@@ -3,8 +3,6 @@
 [buildout]
 extends =
   ../gmp/buildout.cfg
-  ../mpc/buildout.cfg
-  ../mpfr/buildout.cfg
   ../perl/buildout.cfg
   ../tar/buildout.cfg
   ../xz-utils/buildout.cfg

component/headless-chromium/buildout.cfg

 [buildout]
 extends =
+  ../binutils/buildout.cfg
   ../bison/buildout.cfg
   ../pkgconfig/buildout.cfg
   ../gperf/buildout.cfg
@@ -7,7 +8,6 @@ extends =
   ../freetype/buildout.cfg
   ../cmake/buildout.cfg
   ../git/buildout.cfg
-  ../mpfr/buildout.cfg
   ../pkgconfig/buildout.cfg
   ../cups/buildout.cfg
   ../coreutils/buildout.cfg

component/mpc/buildout.cfg

-[buildout]
-extends =
-  ../gmp/buildout.cfg
-  ../mpfr/buildout.cfg
-
-parts =
-  mpc
-  
-[mpc]
-recipe = slapos.recipe.cmmi
-url = http://ftp.gnu.org/gnu/mpc/mpc-1.0.3.tar.gz
-md5sum = d6a1d5f8ddea3abd2cc3e98f58352d26
-configure-options =
-  --with-gmp=${gmp:location}
-  --with-mpfr=${mpfr:location}
-  --disable-static
-environment =
-  LDFLAGS=-Wl,-rpath=${gmp:location}/lib -Wl,-rpath=${mpfr:location}/lib
\ No newline at end of file

component/mpfr/buildout.cfg

-[buildout]
-extends = 
-  ../gmp/buildout.cfg
-  ../xz-utils/buildout.cfg
-
-[mpfr]
-recipe = slapos.recipe.cmmi
-url = http://ftp.gnu.org/gnu/mpfr/mpfr-3.1.3.tar.xz
-md5sum = 6969398cd2fbc56a6af570b5273c56a9
-configure-options =
-  --with-gmp=${gmp:location}
-  --disable-static
-environment =
-  PATH=${xz-utils:location}/bin:%(PATH)s
-  LDFLAGS=-Wl,-rpath=${gmp:location}/lib
\ No newline at end of file