Respect user-flags for LTO
--- a/cmake/BTApplication.cmake
+++ b/cmake/BTApplication.cmake
@@ -110,15 +110,6 @@ IF(BUILD_TEXT_TO_SPEECH)
 ENDIF()
 SET_TARGET_PROPERTIES("bibletime" PROPERTIES CXX_EXTENSIONS NO)
 
-SET(CMAKE_REQUIRED_QUIET TRUE)
-INCLUDE(CheckIPOSupported)
-CHECK_IPO_SUPPORTED(RESULT HAVE_IPO)
-MESSAGE(STATUS "Using interprocedural optimization: ${HAVE_IPO}")
-IF(HAVE_IPO)
-    SET_TARGET_PROPERTIES("bibletime" PROPERTIES
-        INTERPROCEDURAL_OPTIMIZATION TRUE)
-ENDIF()
-
 INCLUDE(CheckCXXCompilerFlag)
 FOREACH(flag IN ITEMS
     "-Walloca"