os: TestStdPipe fails in AIX

[ayappanec]

--- FAIL: TestStdPipe (178.15s)
    exec.go:213: test timed out while running command: /ramdisk8GB/workdir-host-aix-ppc64-osuosl/tmp/go-build761362951/b139/os.test -test.run TestStdPipe
    pipe_test.go:142: unexpected exit status signal: killed for descriptor 1 sig false
    exec.go:213: test timed out while running command: /ramdisk8GB/workdir-host-aix-ppc64-osuosl/tmp/go-build761362951/b139/os.test -test.run TestStdPipe
    pipe_test.go:142: unexpected exit status signal: killed for descriptor 2 sig false
    exec.go:213: test timed out while running command: /ramdisk8GB/workdir-host-aix-ppc64-osuosl/tmp/go-build761362951/b139/os.test -test.run TestStdPipe
    pipe_test.go:160: unexpected exit status signal: killed for write to closed stdout
panic: test timed out after 3m0s
	running tests:
		TestRootCreate (0s)
		TestRootCreate/symlink_chain (0s)

goroutine 449 gp=0xa00000049d821c0 m=6 mp=0xa00000049d2e008 [running]:
panic({0x11001a0b0?, 0xa00000049e21150?})
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/panic.go:877 +0x1b8 fp=0xa00000049d65ee0 sp=0xa00000049d65e20 pc=0x10009d0a8
testing.(*M).startAlarm.func1()
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2795 +0x318 fp=0xa00000049d65fc0 sp=0xa00000049d65ee0 pc=0x10013a3a8
runtime.goexit({})
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/asm_ppc64x.s:1097 +0x4 fp=0xa00000049d65fc0 sp=0xa00000049d65fc0 pc=0x1000a5b04
created by time.goFunc
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/time/sleep.go:215 +0x60

goroutine 1 gp=0xa00000049c9c1c0 m=nil [chan receive]:
runtime.gopark(0xa0000004a25e008?, 0xa0000004a035100?, 0xa?, 0x0?, 0xa00000046c744e8?)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/proc.go:464 +0x14c fp=0xa00000049d57860 sp=0xa00000049d57828 pc=0x10009d58c
runtime.chanrecv(0xa0000004a035100, 0xa00000049d5799f, 0x1)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/chan.go:667 +0x56c fp=0xa00000049d57900 sp=0xa00000049d57860 pc=0x10000f4bc
runtime.chanrecv1(0x18?, 0x1100404d0?)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/chan.go:509 +0x10 fp=0xa00000049d57938 sp=0xa00000049d57900 pc=0x10000ef10
testing.(*T).Run(0xa00000049e58008, {0x10023d8a1?, 0x1001355f8?}, 0x110068ad0)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2102 +0x4dc fp=0xa00000049d57a20 sp=0xa00000049d57938 pc=0x10013666c
testing.runTests.func1(0xa00000049e58008)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2578 +0x50 fp=0xa00000049d57a70 sp=0xa00000049d57a20 pc=0x100138ca0
testing.tRunner(0xa00000049e58008, 0xa00000049d57bc0)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2029 +0x114 fp=0xa00000049d57ad0 sp=0xa00000049d57a70 pc=0x100135654
testing.runTests({0x0, 0x0}, {0x1002395c4, 0x2}, 0xa00000049e3e120, {0x1101e3640, 0xed, 0xed}, {0x0?, 0xa00000049e11128?, ...})
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2576 +0x544 fp=0xa00000049d57be0 sp=0xa00000049d57ad0 pc=0x100138bb4
testing.(*M).Run(0xa00000049e2e280)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/testing/testing.go:2436 +0x7a0 fp=0xa00000049d57e38 sp=0xa00000049d57be0 pc=0x1001374c0
os_test.TestMain(0xa00000049e2e280)
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/os/os_test.go:40 +0xdc fp=0xa00000049d57e90 sp=0xa00000049d57e38 pc=0x1001e535c
main.main()
	_testmain.go:562 +0x9c fp=0xa00000049d57f30 sp=0xa00000049d57e90 pc=0x10023719c
runtime.main()
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/proc.go:289 +0x370 fp=0xa00000049d57fc0 sp=0xa00000049d57f30 pc=0x1000612a0
runtime.goexit({})
	/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/src/runtime/asm_ppc64x.s:1097 +0x4 fp=0xa00000049d57fc0 sp=0xa00000049d57fc0 pc=0x1000a5b04

https://build.golang.org/log/eae5064aad4ab05a9c2f121d5b4b6f93c74a2265

[mknyszek]

CC @golang/aix