runtime: adjust address calculation in identifying abort on windows/arm

Apparently we're being called on arm 1 byte off, just like on 386 and
amd64, so unify the handler for isAbortPC.

Fixes #42859.
Updates #29050.

Change-Id: I97fffeb4a33d93ca3397ce1c9ba2b05137f391ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/273727
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Trust: Alex Brainman <alex.brainman@gmail.com>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
diff --git a/src/runtime/signal_windows.go b/src/runtime/signal_windows.go
index 6d98d02..3af2e39 100644
--- a/src/runtime/signal_windows.go
+++ b/src/runtime/signal_windows.go
@@ -43,16 +43,9 @@
 //
 //go:nosplit
 func isAbort(r *context) bool {
-	switch GOARCH {
-	case "386", "amd64":
-		// In the case of an abort, the exception IP is one byte after
-		// the INT3 (this differs from UNIX OSes).
-		return isAbortPC(r.ip() - 1)
-	case "arm":
-		return isAbortPC(r.ip())
-	default:
-		return false
-	}
+	// In the case of an abort, the exception IP is one byte after
+	// the INT3 (this differs from UNIX OSes).
+	return isAbortPC(r.ip() - 1)
 }
 
 // isgoexception reports whether this exception should be translated