unix: add Getresuid and Getresgid for OpenBSD

Addresses golang/go#60483 for OpenBSD.

This change was successfully tested on amd64 and adjusted accordingly for the other architectures.

Change-Id: Id63cca342d81d2cc5854eb2923ca7e66bfaa91bf
GitHub-Last-Rev: cff11701438edc20bef2961bb73bf9c6ea81b4a1
GitHub-Pull-Request: golang/sys#160
Reviewed-on: https://go-review.googlesource.com/c/sys/+/500655
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/unix/zsyscall_openbsd_riscv64.s b/unix/zsyscall_openbsd_riscv64.s
index 990be24..477a7d5 100644
--- a/unix/zsyscall_openbsd_riscv64.s
+++ b/unix/zsyscall_openbsd_riscv64.s
@@ -158,6 +158,16 @@
 GLOBL	·libc_getcwd_trampoline_addr(SB), RODATA, $8
 DATA	·libc_getcwd_trampoline_addr(SB)/8, $libc_getcwd_trampoline<>(SB)
 
+TEXT libc_getresuid_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	libc_getresuid(SB)
+GLOBL	·libc_getresuid_trampoline_addr(SB), RODATA, $8
+DATA	·libc_getresuid_trampoline_addr(SB)/8, $libc_getresuid_trampoline<>(SB)
+
+TEXT libc_getresgid_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	libc_getresgid(SB)
+GLOBL	·libc_getresgid_trampoline_addr(SB), RODATA, $8
+DATA	·libc_getresgid_trampoline_addr(SB)/8, $libc_getresgid_trampoline<>(SB)
+
 TEXT libc_ioctl_trampoline<>(SB),NOSPLIT,$0-0
 	JMP	libc_ioctl(SB)
 GLOBL	·libc_ioctl_trampoline_addr(SB), RODATA, $8