tested on

Linux Debian 3.16.0-4-686-pae #1 SMP Debian 3.16.7-ckt20-1+deb8u2 (2016-01-02) i686 GNU/Linux
wget ftp://ftp.fu-berlin.de/unix/languages/gcc/releases/gcc-5.3.0/gcc-5.3.0.tar.bz2; # download sources
bunzip2 gcc-5.3.0.tar.bz2; # unpack sources
tar fx gcc-5.3.0.tar; # untar
apt-get update;
apt-get install libmpc-dev; # install dependencies
cd gcc-5.3.0; # enter dir of sources
./configure; # Guess values for system-dependent variables and create Makefiles.
make; # build

links:

http://stackoverflow.com/questions/9253695/building-gcc-requires-gmp-4-2-mpfr-2-3-1-and-mpc-0-8-0

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