Multi threaded fitting and returning chi2 (#132)

Co-authored-by: Patrick <patrick.sieberer@psi.ch>
Co-authored-by: JulianHeymes <julian.heymes@psi.ch>
Co-authored-by: Dhanya Thattil <dhanya.thattil@psi.ch>

CMakeLists.txt

@@ -85,7 +85,7 @@ if(AARE_FETCH_LMFIT)
         GIT_TAG        main
         PATCH_COMMAND ${lmfit_patch}
         UPDATE_DISCONNECTED 1
-        EXCLUDE_FROM_ALL
+        EXCLUDE_FROM_ALL 1
     )
     #Disable what we don't need from lmfit
     set(BUILD_TESTING OFF CACHE BOOL "")
@@ -97,9 +97,6 @@ if(AARE_FETCH_LMFIT)
     
     FetchContent_MakeAvailable(lmfit)
     set_property(TARGET lmfit PROPERTY POSITION_INDEPENDENT_CODE ON)
-
-    target_include_directories (lmfit PUBLIC "${libzmq_SOURCE_DIR}/lib")
-    message(STATUS "lmfit include dir: ${lmfit_SOURCE_DIR}/lib")
 else()
     find_package(lmfit REQUIRED)
 endif()
@@ -370,7 +367,8 @@ target_link_libraries(
     ${STD_FS_LIB} # from helpers.cmake
     PRIVATE 
     aare_compiler_flags 
-    lmfit
+    "$<BUILD_INTERFACE:lmfit>"
+
 )
 
 set_target_properties(aare_core PROPERTIES