"apt-get install libmpfr-dev:i386" wants to remove gcc, while this
is not needed:

# apt-get install libmpfr-dev:i386
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
  libcloog-isl4:i386 libisl10:i386 libmpc3:i386 ocaml-base zlib1g:i386
Use 'apt-get autoremove' to remove it.
The following extra packages will be installed:
  libasan0:i386 libatomic1:i386 libc6-dev:i386 libgcc-4.8-dev:i386
  libgmp-dev:i386 libgmp10:i386 libgmpxx4ldbl:i386 libgomp1:i386 libitm1:i386
  libmpfr4:i386 libquadmath0:i386 libstdc++-4.8-dev:i386 libstdc++6:i386
  linux-libc-dev:i386
Suggested packages:
  manpages-dev:i386 libgmp10-doc:i386 libmpfr-doc:i386 libstdc++-4.8-doc:i386
Recommended packages:
  gcc:i386 c-compiler:i386 libstdc++-dev:i386
The following packages will be REMOVED:
  build-essential camlp4 dh-buildinfo g++ g++-multilib gcc gcc-multilib
  gfortran gnulib hardening-wrapper lcov ocaml ocaml-nox
The following NEW packages will be installed:
  libasan0:i386 libatomic1:i386 libc6-dev:i386 libgcc-4.8-dev:i386
  libgmp-dev:i386 libgmp10:i386 libgmpxx4ldbl:i386 libgomp1:i386 libitm1:i386
  libmpfr-dev:i386 libmpfr4:i386 libquadmath0:i386 libstdc++-4.8-dev:i386
  libstdc++6:i386 linux-libc-dev:i386
0 upgraded, 15 newly installed, 13 to remove and 10 not upgraded.
Need to get 13.7 MB of archives.
After this operation, 88.0 MB disk space will be freed.
Do you want to continue [Y/n]? ^C

# apt-get install libmpfr-dev:i386 gcc
Reading package lists... Done
Building dependency tree
Reading state information... Done
gcc is already the newest version.
The following extra packages will be installed:
  libasan0:i386 libatomic1:i386 libc6-dev:i386 libgcc-4.8-dev:i386
  libgmp-dev:i386 libgmp10:i386 libgmpxx4ldbl:i386 libgomp1:i386 libitm1:i386
  libmpfr4:i386 libquadmath0:i386 libstdc++-4.8-dev:i386 libstdc++6:i386
  linux-libc-dev:i386
Suggested packages:
  manpages-dev:i386 libgmp10-doc:i386 libmpfr-doc:i386 libstdc++-4.8-doc:i386
Recommended packages:
  gcc:i386 c-compiler:i386 libstdc++-dev:i386
The following NEW packages will be installed:
  libasan0:i386 libatomic1:i386 libc6-dev:i386 libgcc-4.8-dev:i386
  libgmp-dev:i386 libgmp10:i386 libgmpxx4ldbl:i386 libgomp1:i386 libitm1:i386
  libmpfr-dev:i386 libmpfr4:i386 libquadmath0:i386 libstdc++-4.8-dev:i386
  libstdc++6:i386 linux-libc-dev:i386
0 upgraded, 15 newly installed, 0 to remove and 10 not upgraded.
Need to get 13.7 MB of archives.
After this operation, 45.8 MB of additional disk space will be used.
Do you want to continue [Y/n]?

I've attached the /var/lib/dpkg/status file, compressed.