Build LLVMgold.so on FreeBSD using cmake.
Patch by Stephen Checkoway.

llvm-svn: 177233
diff --git a/llvm/tools/CMakeLists.txt b/llvm/tools/CMakeLists.txt
index 4cf5aa5..5e95604 100644
--- a/llvm/tools/CMakeLists.txt
+++ b/llvm/tools/CMakeLists.txt
@@ -49,7 +49,8 @@
 
 if( LLVM_ENABLE_PIC )
   # TODO: support other systems:
-  if( CMAKE_SYSTEM_NAME STREQUAL "Linux" )
+  if( (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+      OR (CMAKE_SYSTEM_NAME STREQUAL "FreeBSD") )
     add_subdirectory(gold)
   endif()
 endif()