When loading a module supporting multiple targets, the module loader now looks for a file named with a normalized version of the target triple first, and only falls back to the architecture name if the normalized triple is not found.
This diagnostic needs to be adapted for swiftinterfaces too, but
meanwhile let's not have it get in the way when dealing with a
multi-architecture module that has parseable interfaces.
MyKit.framework/
Modules/
MyKit.swiftmodule/
x86_64.swiftinterface
x86_64.swiftdoc
# no x86_64.swiftmodule
armv7, armv7s, and armv7k all get encoded as "arm" in today's scheme
for swiftmodules, so we can't just use the CPU part of the triple as
the expected swiftmodule architecture in the diagnostic.
