cmd/dist: get testcarchive working on iOS

[crawshaw]

cl/110400043 disables some tests because of the lack of compiler on android. Find a way
to get them working again.

[minux]

Comment 1:

Labels changed: added repo-main, release-go1.4.

[crawshaw]

Comment 2:

In particular:
- the runtime tests that depend on a compiler on the target. (e.g. crash_test.go)
- the cgo tests in run.bash that depend on test/run.go
The latter will require plumbing knowledge of GOHOSTOS/GOOS through run.go.

[minux]

Comment 3:

misc/cgo tests breakdown:
misc/cgo/stdio, misc/cgo/life aren't important, they are just cgo examples;
misc/cgo/test: the most important one, shouldn't be too hard to run;
misc/cgo/testcdefs: should be covered by other systems;
misc/cgo/testso: test cgo could link dynamic libraries, covered by normal android cgo
usage;
misc/cgo/testasan: not relevant on 32-bit systems;
misc/cgo/errors: covered by other systems.
In summary: we need to run misc/cgo/test and various crash tests from runtime.
I don't think we need to modify test/run.go.

[rsc]

Comment 4:

Labels changed: added release-go1.5, removed release-go1.4.