install_name_tool -rpath fails with error on some plugins

Some of the plugin binaries fail with an error when running one of the install_name_tool RPATH options (e.g. -rpath, -delete_rpath):

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/install_name_tool: fatal error: file not in an order that can be processed (link edit information does not fill the __LINKEDIT segment): libqjpeg.dylib (for architecture x86_64)

For example, this happens with imageformats/libqjpeg.dylib, but not imageformats/libqsvg.dylib. This is for the prebuilt binaries in the 6.8.0 release candidate. Also, this is after removing the existing signature with `codesign --remove-signature`. I don't know how far back this goes, but it was working in 6.6.3.