Use 'svn' for the version suffix

This was accidentally changed in a previous merge resolution.

Author: Dylan McKay

CMakeLists.txt

@@ -29,7 +29,7 @@ if(NOT DEFINED LLVM_VERSION_PATCH)
   set(LLVM_VERSION_PATCH 0)
 endif()
 if(NOT DEFINED LLVM_VERSION_SUFFIX)
-  set(LLVM_VERSION_SUFFIX "")
+  set(LLVM_VERSION_SUFFIX svn)
 endif()
 
 if (POLICY CMP0048)