gollvm: update cmake for recent libgo changes

This CL updates gollvm's libgo cmake recipes to bring them into
sync with a recent gofrontend change involving osinit in

Change-Id: If60783ba7ea7df2efb51c55f78c7cb594078221d
Reviewed-on: https://go-review.googlesource.com/c/gollvm/+/191745
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/libgo/CMakeLists.txt b/libgo/CMakeLists.txt
index 3db46ee..e28cc61 100644
--- a/libgo/CMakeLists.txt
+++ b/libgo/CMakeLists.txt
@@ -438,7 +438,6 @@
 # Linux-specific C files.
 if(${goos} STREQUAL "linux")
   list(APPEND runtimecfiles
-    "runtime/getncpu-linux.c"