Eliminating compilation warnings when using lto in

gcc12 and later versions

use -flto=auto when use gcc12 or later

Signed-off-by: 不鱼儿 <36976072+buyuer@users.noreply.github.com>

cmake/OpenCVCompilerOptions.cmake

@@ -261,7 +261,11 @@ if(CV_GCC OR CV_CLANG)
   endif()
 
   if(ENABLE_LTO)
-    add_extra_compiler_option(-flto)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 12)
+      add_extra_compiler_option(-flto=auto)
+    else()
+      add_extra_compiler_option(-flto)
+    endif()
   endif()
   if(ENABLE_THIN_LTO)
     add_extra_compiler_option(-flto=thin)