runtime/internal/startlinetest: work around shared buildmode linking issue
The runtime/internal/startlinetest package contains a call to a
function defined in runtime_test. Generally this is fine as this
package is only linked in for runtime_test. Except that for "go
install -buildmode=shared std", which include all packages in std,
including this test-only internal package. In this mode, the
caller is included in the linking but the callee is not, causing
linking error. Work around it by calling
runtime_test.callerStartLine via a function pointer. The function
pointer is only set in runtime_test. In the shared std build, the
function pointer will not be set, and this is fine.
Fixes #57334.
Change-Id: I7d871c50ce6599c6ea2802cf6e14bb749deab220
Reviewed-on: https://go-review.googlesource.com/c/go/+/458696
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>