Define EXIV2_ENABLE_DYNAMIC_RUNTIME only once

CMakeLists.txt

@@ -36,15 +36,14 @@ OPTION( EXIV2_ENABLE_BUILD_SAMPLES "Build the unit tests"
 OPTION( EXIV2_ENABLE_BUILD_PO      "Build translations files"                              OFF )
 OPTION( EXIV2_ENABLE_VIDEO         "Build video support into library"                      OFF )
 OPTION( EXIV2_ENABLE_WEBREADY      "Build webready support into library"                   OFF )
+OPTION( EXIV2_ENABLE_DYNAMIC_RUNTIME  "Use dynamic runtime (used for static libs)"         OFF )
 IF (WIN32)
-    OPTION( EXIV2_ENABLE_DYNAMIC_RUNTIME  "Use dynamic runtime (used for static libs)"     OFF )
     OPTION( EXIV2_ENABLE_WIN_UNICODE   "Use Unicode paths (wstring) on Windows"            OFF )
     OPTION( EXIV2_ENABLE_CURL          "USE Libcurl for HttpIo"                            OFF )
     OPTION( EXIV2_ENABLE_SSH           "USE Libssh for SshIo"                              OFF )
 ELSE()
     OPTION( EXIV2_ENABLE_CURL          "USE Libcurl for HttpIo"                            ON  )
     OPTION( EXIV2_ENABLE_SSH           "USE Libssh for SshIo"                              ON  )
-    SET ( EXIV2_ENABLE_DYNAMIC_RUNTIME OFF )
 ENDIF()
 OPTION( EXIV2_ENABLE_TOOLS         "Build exiv2 executable"                                ON  )