unix: make Prlimit public

glibc has a wrapper for it, so why shouldn't we?

Change-Id: I5c6e24c8e567e0198ea679f0be33e2eff056d5ed
Reviewed-on: https://go-review.googlesource.com/c/sys/+/332029
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
diff --git a/unix/syscall_linux_arm.go b/unix/syscall_linux_arm.go
index 39a864d..b961a62 100644
--- a/unix/syscall_linux_arm.go
+++ b/unix/syscall_linux_arm.go
@@ -184,7 +184,7 @@
 const rlimInf64 = ^uint64(0)
 
 func Getrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, nil, rlim)
+	err = Prlimit(0, resource, nil, rlim)
 	if err != ENOSYS {
 		return err
 	}
@@ -212,7 +212,7 @@
 //sysnb	setrlimit(resource int, rlim *rlimit32) (err error) = SYS_SETRLIMIT
 
 func Setrlimit(resource int, rlim *Rlimit) (err error) {
-	err = prlimit(0, resource, rlim, nil)
+	err = Prlimit(0, resource, rlim, nil)
 	if err != ENOSYS {
 		return err
 	}