internal/cpu: correctly link to getsystemcfg

Directly set getsystemcfg as //extern in internal/cpu instead of
trying to use the runtime as in Go toolchain.

Change-Id: I2a095fd471f20be33205c160607b749dd04a017c
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/287932
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Cherry Zhang <cherryyz@google.com>
diff --git a/libgo/go/internal/cpu/cpu_ppc64x_aix.go b/libgo/go/internal/cpu/cpu_ppc64x_aix.go
index a932684..e2422a6 100644
--- a/libgo/go/internal/cpu/cpu_ppc64x_aix.go
+++ b/libgo/go/internal/cpu/cpu_ppc64x_aix.go
@@ -17,5 +17,5 @@
 	PPC64.IsPOWER9 = isSet(impl, _IMPL_POWER9)
 }
 
-// getsystemcfg is defined in runtime/os2_aix.go
+//extern getsystemcfg
 func getsystemcfg(label uint) uint
diff --git a/libgo/go/runtime/os_aix.go b/libgo/go/runtime/os_aix.go
index 630a1c2..d902ae0 100644
--- a/libgo/go/runtime/os_aix.go
+++ b/libgo/go/runtime/os_aix.go
@@ -13,9 +13,6 @@
 //extern sysconf
 func sysconf(int32) _C_long
 
-//extern getsystemcfg
-func getsystemcfg(int32) uint64
-
 type mOS struct {
 	waitsema uintptr // semaphore for parking on locks
 }