OK, in that case, I'd say specifying it in the easyblock is overkill. Just drop it then, I don't really care much for build time.
And actually, you can set it easily using `configopts` in the easyconfig file, or even on the command line with `--try-amend="configopts='-DLLVM_TARGETS_TO_BUILD=X86' " (or using `$EASYBUILD_AMEND="configopts='-DLLVM_TARGETS_TO_BUILD=X86' "`). :)