input: [Field] UpdateLibtool [Value] 
output: A boolean value. If true, the files ltconfig and ltmain.sh in the build directory will be replaced with versions that know about Darwin. This happens in the patch phase and before the PatchScript is run. Only use this when you know that the package needs it. Some packages can be broken by overwriting the libtool scripts with mismatching versions. See the libtool page for further information.