gtranslator specifies -Werror in a makefile deep down in the source directories, and erroneously ignores passing --enable-compile-warnings=all (instead of --enable-compile-warnings=error). Even --disable-compile-warnings is totally ignored. Patch attached the removes -Werror from that particular makefile.am and reruns automake, to allow the package to compile under GCC 4. It's not pretty, much warnings about pointer signedness, but the package compiles and appears to work properly.
Created attachment 61057 [details, diff] gtranslator-1.1.5.ebuild.diff Promised ebuild diff
This has been rectified in gtranslator-1.1.6, so instead of applying the patch it is also possible to bump the package instead. (Or do both)
Version bumped to 1.1.6 in portage tree; ack'd by AllanonJL on IRC.