gollvm: emit func descriptors constant to cpugen.go

Update the cmake rules for generating cpugen.go to emit a definition
to control use of function descriptors. See gofrontend CL 162978 for
more info.

Change-Id: I0d335e8425d73fb9ac9bc28171851a9be2107f87
Reviewed-on: https://go-review.googlesource.com/c/164638
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/cmake/modules/AutoGenGo.cmake b/cmake/modules/AutoGenGo.cmake
index b5ea13f..741118ab 100644
--- a/cmake/modules/AutoGenGo.cmake
+++ b/cmake/modules/AutoGenGo.cmake
@@ -142,11 +142,14 @@
       ERROR_VARIABLE errmsg
       RESULT_VARIABLE exitstatus)
     if(${exitstatus} MATCHES 0)
-      file(APPEND ${outfile} "const CacheLinePadSize = ${result}")
+      file(APPEND ${outfile} "const CacheLinePadSize = ${result}\n")
       message(FATAL_ERROR "goarch.sh invocation failed: ${errmsg}")
-    file(APPEND ${outfile} "\n\n")
+    # For now this is hard-wired off. If/when gollvm supports
+    # PPC64 ELF ABI v1 we'll need to configure it.
+    file(APPEND ${outfile} "const FunctionDescriptors = false\n")
+    file(APPEND ${outfile} "\n")