Added a note about a possible solution for bug 335 (#370)

src/CMakeLists.txt

@@ -2,14 +2,19 @@ find_package(LibYANG REQUIRED)
 
 include_directories(${CMAKE_SOURCE_DIR}/src/libs/bcc/src/cc/libbpf/include/uapi)
 
-option(INSTALL_CLI "installs the polycube CLI" ON)
-option(ENABLE_PCN_IPTABLES "enables the pcn-iptables" OFF)
+option(INSTALL_CLI "Installs the polycube CLI" ON)
+option(ENABLE_PCN_IPTABLES "Enables the pcn-iptables" OFF)
+
+# The following is the default option for bcc: embedding LLVM in the lib files.
+# However, somebody filled an issue (#335) such as "Option XXXXXX registered more than once"
+# Apparently, this could be solved by turning the following flag to ON
+option(ENABLE_LLVM_SHARED "Enable linking LLVM as a shared library" OFF)
 
 add_subdirectory(components)
 add_subdirectory(libs)
 
-# it fills a list with the name of all enabled services, that list is used by
-# the cmake in polycubed, for that reason it has to be added before.
+# It fills a list with the name of all enabled services. That list is used by
+# cmake in polycubed, for that reason it has to be added before.
 
 add_subdirectory(services)