CMake: Fix non-PCH build.

src/server/CMakeLists.txt

@@ -12,6 +12,10 @@
 # This to stop a few silly crashes that could have been avoided IF people
 # weren't doing some -O3 psychooptimizations etc.
 
+include_directories(
+${Boost_INCLUDE_DIR}
+)
+
 if(CMAKE_COMPILER_IS_GNUCXX AND NOT MINGW)
   add_definitions(-fno-delete-null-pointer-checks)
 endif()