This layout parameter is currently always nil and ignored, but will
eventually contain a pointer to a memory layout.
This commit also adds module verification to the transform tests, as I
found out that it didn't (and therefore didn't initially catch all
bugs).
The copy builtin is defined as follows by the Go language spec:
copy(dst, src []T) int
copy(dst []byte, src string) int
In other words, it returns an int. The runtime.sliceCopy compiler
intrinsic returned a uintptr instead, which led to a problem while
compiling the strings package for AVR.
No other architecture should be affected by this change as the
conversion from an uintptr to an int is a no-op on most architectures.
* Use 64-bit integers on 64-bit platforms, just like gc and gccgo:
https://golang.org/doc/go1.1#int
* Do not use a separate length type. Instead, use uintptr everywhere a
length is expected.
