Revert CMAKE_FIND_PACKAGE_PREFER_CONFIG as its from cmake > 3.13

Do the overriding in the appropriate find modules in cmake/modules

CMakeLists.txt

@@ -43,14 +43,6 @@ set(SLIC3R_GTK "2" CACHE STRING "GTK version to use with wxWidgets on Linux")
 
 set(IS_CROSS_COMPILE FALSE)
 
-if (SLIC3R_STATIC)
-    # Prefer config scripts over find modules. This is helpful when building with
-    # the static dependencies. Many libraries have their own export scripts
-    # while having a Find<PkgName> module in standard cmake installation.
-    # (e.g. CURL)
-    set(CMAKE_FIND_PACKAGE_PREFER_CONFIG ON)
-endif ()
-
 if (APPLE)
     set(CMAKE_FIND_FRAMEWORK LAST)
     set(CMAKE_FIND_APPBUNDLE LAST)
@@ -458,19 +450,10 @@ if (NOT EIGEN3_FOUND)
 endif ()
 include_directories(BEFORE SYSTEM ${EIGEN3_INCLUDE_DIR})
 
-# Find expat or use bundled version
-# Always use the system libexpat on Linux.
-
+# Find expat. We have our overriden FindEXPAT which exports libexpat target
+# no matter what.
 find_package(EXPAT REQUIRED)
 
-add_library(libexpat INTERFACE)
-
-if (TARGET EXPAT::EXPAT )
-    target_link_libraries(libexpat INTERFACE EXPAT::EXPAT)
-elseif(TARGET expat::expat)
-    target_link_libraries(libexpat INTERFACE expat::expat)
-endif ()
-
 find_package(PNG REQUIRED)
 
 set(OpenGL_GL_PREFERENCE "LEGACY")

cmake/modules/FindCURL.cmake

@@ -30,6 +30,23 @@
 # ``CURL_VERSION_STRING``
 #   The version of curl found.
 
+# First, prefer config scripts
+set(_q "")
+if(CURL_FIND_QUIETLY)
+    set(_q QUIET)
+endif()
+find_package(CURL ${CURL_FIND_VERSION} CONFIG ${_q})
+
+if(NOT CURL_FIND_QUIETLY)
+    if (NOT CURL_FOUND)
+        message(STATUS "Falling back to MODULE search for CURL...")
+    else()
+        message(STATUS "CURL found in ${CURL_DIR}")
+    endif()
+endif()
+
+if (NOT CURL_FOUND)
+
   # Look for the header file.
   find_path(CURL_INCLUDE_DIR NAMES curl/curl.h)
   mark_as_advanced(CURL_INCLUDE_DIR)
@@ -109,3 +126,5 @@ if(CURL_FOUND)
       endif()
     endif()
   endif()
+
+endif (NOT CURL_FOUND)