Each cross compiler needs tools that are stored under
GOROOT/pkg/tool/GOHOSTOS_GOHOSTARCH: 5g, 5l, etc. This means a
single GOROOT is incompatible with multiple cross compilers for
different GOOS targets that share a GOARCH. In particular, it
means android/arm and darwin/arm cannot co-exist.
To avoid conflicting paths, this CL installs the cross-compiler
tools under GOPATH/pkg/gomobile. The Go tool is instructed to
use them using the new -toolexec flag. This means far less
meddling in the user's GOROOT.
Unfortunately, the standard library .a files (and textflag.h/funcdata.h)
must still be installed under GOROOT/pkg/GOOS_GOARCH. However this path
does not conflict across cross compiler toolchains, nor with the host
toolchain.
Change-Id: I088142281cf441365072c77f4cb73683b5ffd0ce
Reviewed-on: https://go-review.googlesource.com/5040
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
64689dc2a5