misc/cgo/fortran: convert to Go test

Currently, the entry-point to this test is a Bash script that smoke
tests the FORTRAN compiler and then runs a FORTRAN-containing Go test.
This CL rearranges things so a pure Go Go test smoke tests the FORTRAN
compiler and then runs a non-test FORTRAN-containing Go binary.

While we're here, we fix a discrepancy when the host is GOARCH=amd64,
but the target is GOARCH=386. Previously, we would pick the wrong
libgfortran path because we didn't account for the cross-compilation,
causing the link to fail. Except for some reason this was ignored and
the test nevertheless "passed". In the new test we're a little more
strict, so this build failure will cause the test to fail, so we add a
little logic to account for cross-compilation with the host toolchain.

For #37486.

Change-Id: Ie6f70066885d6fbb4e1b5a2b1e13b85dee5b359b
Reviewed-on: https://go-review.googlesource.com/c/go/+/443069
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Austin Clements <austin@google.com>

0 files changed, 0 insertions, 0 deletions