1.check and install libtools    
yum install libtool       
yum install libtool-ltdl    
yum install libtool-ltdl-devel       
2.try run "../gcc-svn/config.sub" through shell
/bin/bash ../gcc-svn/config.sub
see if shows as follows:
[root@centos jemalloc]# /bin/bash ./config.sub
  : command not foundine 6:
  : command not foundine 8:
  : command not foundine 30:
  : command not foundine 31:
  : command not foundine 39:
  : command not foundine 42:
  : command not foundine 50:
  : command not foundine 57:
  : command not foundine 59:
  : command not foundine 72:
  : command not foundine 82:
  : command not foundine 85:
  '/config.sub.bak: line 88:    syntax error near unexpected token in
  '/config.sub.bak: line 88: `  case $1 in
3.find the system config.sub
 find / -name config.sub
it shows:
/usr/share/libtool/config/config.sub
compare the two config.sub to see if they are similar.
4.replace config.sub with system file
mv ../gcc-svn/config.sub ../gcc-svn/config.sub.bak
cp /usr/share/libtool/config/config.sub ../gcc-svn/config.sub 
mv ../gcc-svn/config.guess ../gcc-svn/config.guess.bak
cp /usr/share/libtool/config/config.guess ../gcc-svn/config.guess
- make to see if it works out.