When we unmerged the older version of sys-devel/gcc, it printed out an error message at the end of the unmerge process:

>>> Unmerging sys-devel/gcc-4.1.2...
 * Running 'fix_libtool_files.sh 4.1.2'
 * Scanning libtool files for hardcoded gcc library paths...
gcc-config error: Could not run/locate "gcc"
:0: assertion failed: (gcc -dumpversion) | getline NEWVER)

Then we manually checked around. First, try "gcc-config":

# gcc-config -c
* gcc-config: Active gcc profile is invalid!
 [1] i686-pc-linux-gnu-4.3.2

Now fix that:

# gcc-config 1
 * Switching native-compiler to i686-pc-linux-gnu-4.3.2 ...
 * Your gcc has a bug with GCC_SPECS.
 * Please re-emerge gcc.
 * http://bugs.gentoo.org/68395

Since it asked to re-emerge gcc, so let's do so:

# emerge -v gcc
......
* Messages for package sys-devel/gcc-4.3.2-r3:
 * If you have issues with packages unable to locate libstdc++.la,
 * then try running 'fix_libtool_files.sh' on the old gcc versions.

This looks good. Now lets run fix_libtool_files.sh again:

# fix_libtool_files.sh 4.1.2
 * Scanning libtool files for hardcoded gcc library paths...
 *   [1/5] Scanning /lib ...
 *   [2/5] Scanning /usr/lib ...
 *   [3/5] Scanning /usr/i686-pc-linux-gnu/lib ...
 *   [4/5] Scanning //usr//lib/opengl/xorg-x11/lib ...
 *   [5/5] Scanning /usr/local/lib ...

Verify with gcc-config:

# gcc-config -l
 [1] i686-pc-linux-gnu-4.3.2 *

All looks good.