update CMakeLists for ubuntu 16.04

The previous version did not compile on ubuntu 16.04.
I left the old version, commented, just in case.

cmake_targets/at_commands/CMakeLists.txt

@@ -88,31 +88,47 @@ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -msse4.2 -std=gnu99 -Wall -Wstrict-prototype
 set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -ggdb -DMALLOC_CHECK_=3")
 set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -ggdb -DMALLOC_CHECK_=3 -O2")
 
-#This is to detect nettle version changes between Ubuntu 14.04/16.04
-set ( nettle_cmd "nettle-hash" )
-set ( nettle_arg "-V" )
-execute_process(COMMAND  ${nettle_cmd} ${nettle_arg}   RESULT_VARIABLE rv OUTPUT_VARIABLE ov ERROR_VARIABLE ev)
+##This is to detect nettle version changes between Ubuntu 14.04/16.04
+#set ( nettle_cmd "nettle-hash" )
+#set ( nettle_arg "-V" )
+#execute_process(COMMAND  ${nettle_cmd} ${nettle_arg}   RESULT_VARIABLE rv OUTPUT_VARIABLE ov ERROR_VARIABLE ev)
+#
+#string(REGEX MATCH "[+-]?[0-9]+([.][0-9]+)?" nv ${ov})
+#
+#message("NETTLE_VERSION = ${nv}")
+#
+## we need to remove decimal as floating point arithematic does not work properly with C preprocessor
+#STRING(REGEX REPLACE "[.]" "" nv ${nv})
+#
+#if ("${nv}" STREQUAL "")
+#  message( FATAL_ERROR "The nettle version not detected properly. Try to run build_oai -I again" )
+#endif()
+#
+#set (NETTLE_VERSION "${nv}")
+#add_definitions("-DNETTLE_VERSION=${NETTLE_VERSION}")
 
-string(REGEX MATCH "[+-]?[0-9]+([.][0-9]+)?" nv ${ov})
+include(FindPkgConfig)
 
-message("NETTLE_VERSION = ${nv}")
+pkg_search_module(NETTLE nettle)
+if(NOT ${NETTLE_FOUND})
+  message( FATAL_ERROR "PACKAGE nettle not found: some targets will fail. Run build_oai -I again!")
+else()
+  include_directories(${NETTLE_INCLUDE_DIRS})
+endif()
+
+message ("NETTLE VERSION_INSTALLED  = ${NETTLE_VERSION}")
 
-# we need to remove decimal as floating point arithematic does not work properly with C preprocessor
-STRING(REGEX REPLACE "[.]" "" nv ${nv})
+string(REGEX REPLACE "([0-9]+).*" "\\1" NETTLE_VERSION_MAJOR ${NETTLE_VERSION})
+string(REGEX REPLACE "[0-9]+\\.([0-9]+).*" "\\1" NETTLE_VERSION_MINOR ${NETTLE_VERSION})
+message ("NETTLE_VERSION_MAJOR = ${NETTLE_VERSION_MAJOR}")
+message ("NETTLE_VERSION_MINOR = ${NETTLE_VERSION_MINOR}")
 
-if ("${nv}" STREQUAL "")
+if ("${NETTLE_VERSION_MAJOR}" STREQUAL "" OR "${NETTLE_VERSION_MINOR}" STREQUAL "")
   message( FATAL_ERROR "The nettle version not detected properly. Try to run build_oai -I again" )
 endif()
 
-set (NETTLE_VERSION "${nv}")
-add_definitions("-DNETTLE_VERSION=${NETTLE_VERSION}")
-
-include(FindPkgConfig)
-
-INCLUDE(FindNettle)
-IF( NOT NETTLE_FOUND )
-  MESSAGE( SEND_ERROR "Nettle is required" )
-ENDIF( NOT NETTLE_FOUND )
+add_definitions("-DNETTLE_VERSION_MAJOR=${NETTLE_VERSION_MAJOR}")
+add_definitions("-DNETTLE_VERSION_MINOR=${NETTLE_VERSION_MINOR}")
 
 
 pkg_search_module(OPENSSL openssl REQUIRED)