(from http://patch-tracker.debian.org/patch/series/view/icu/4.4.1-7/arm-assembler.patch)

We never used cairocanvas on Mac, this got accidentally enabled
due to configure.in cleanups. Not that we shouldn't, but it needs
some more fixing.

...as they have further dependencies on modules higher up in the hierarchy.

Hardcoding dll names from SuSE Linux in configure.in is not good,
because they might be slightly different on other systems (notably
Fedora :-), or the libraries might be compiled with different
dependencies.

This uses the same pattern that is already used to discriminate env.
vars for host and build (i.e., the new option specific for build
platform has -for-build suffix).

It is implemented for Executable, Library and StaticLibrary and works
for C, C++, Objective C and Objective C++ sources.

Please, do not misuse! Better fix your code!

Also rename private subroutines to start with an underscore.