test: adjust tests for riscv64

This disables some tests that are unsupported on riscv64 and adds support
for risc64 to test/nosplit.

Updates #27532, #36739 and #36765

Change-Id: I0a57797a05bc80236709fc240c0a0efb0ee0d16b
Reviewed-on: https://go-review.googlesource.com/c/go/+/216263
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

test/fixedbugs/issue10607.go

@@ -1,4 +1,4 @@
-// +build linux,!ppc64
+// +build linux,!ppc64,!riscv64
 // run
 
 // Copyright 2015 The Go Authors. All rights reserved.
@@ -8,6 +8,9 @@
 // Test that a -B option is passed through when using both internal
 // and external linking mode.
 
+// TODO(jsing): Re-enable on riscv64 when it has support for external
+// linking - see golang.org/issue/36739
+
 package main
 
 import (

test/inline_sync.go

@@ -1,4 +1,4 @@
-// +build !nacl,!386,!wasm,!arm,!gcflags_noopt
+// +build !nacl,!386,!wasm,!arm,!riscv64,!gcflags_noopt
 // errorcheck -0 -m
 
 // Copyright 2019 The Go Authors. All rights reserved.
@@ -14,6 +14,9 @@
 // of the sync fast paths. This test should be re-enabled once the problem
 // is solved.
 
+// TODO(jsing): Re-enable on riscv64 when it has atomic intrinsics - see
+// golang.org/issue/36765
+
 package foo
 
 import (

test/nosplit.go

@@ -283,6 +283,9 @@ TestCases:
 		case "amd64":
 			ptrSize = 8
 			fmt.Fprintf(&buf, "#define REGISTER AX\n")
+		case "riscv64":
+			ptrSize = 8
+			fmt.Fprintf(&buf, "#define REGISTER A0\n")
 		case "s390x":
 			ptrSize = 8
 			fmt.Fprintf(&buf, "#define REGISTER R10\n")