Some .la files like libgfortran.la libgfortranbegin.la libgomp.la installed by gcc-4.3 are broken: In their last line libdir='...' the "=" sign is missing. This lets compilation fail at least for the packages sci-libs/arpack-96-r2 (for libgfortran*) media-gfx/imagemagick-6.4.4.6 (for libgomp)
Please note that this is _not_ a dupe of bug 258957.
But I guess it is a dupe of Bug #256636. As a broken toolchain.eclass lead to those missing "=". Sadly it was broken just at the time gcc-4.3.3 ebuild was added. *** This bug has been marked as a duplicate of bug 256636 ***