Fix ghc stack overflow while building server
--- CMakeLists.txt.orig	2015-01-06 23:55:59.000000000 +0300
+++ CMakeLists.txt	2015-01-24 22:39:01.000000000 +0300
@@ -108,7 +108,7 @@
     endif()
 endif()
 
-list(APPEND haskell_flags ${ghflags_parsed} "-O2")
+list(APPEND haskell_flags ${ghflags_parsed})
 
 #get BUILD_TYPE and enable/disable optimisation
 message(STATUS "Using ${CMAKE_BUILD_TYPE} configuration")