OpenEXR doesn't build with /ehcont (#454)

build/CompilerAndLinker.cmake

@@ -45,6 +45,7 @@ if(MSVC)
 
     if((MSVC_VERSION GREATER_EQUAL 1928)
        AND (CMAKE_SIZEOF_VOID_P EQUAL 8)
+       AND (NOT (TARGET OpenEXR::OpenEXR))
        AND ((NOT (CMAKE_CXX_COMPILER_ID MATCHES "Clang|IntelLLVM")) OR (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 13.0)))
           list(APPEND COMPILER_SWITCHES "$<$<NOT:$<CONFIG:DEBUG>>:/guard:ehcont>")
           list(APPEND LINKER_SWITCHES "$<$<NOT:$<CONFIG:DEBUG>>:/guard:ehcont>")