cmake/LibXML2: drop linking with libiconv on linux

as it's a part of libc

indra/cmake/LibXML2.cmake

@@ -14,7 +14,7 @@ else(USESYSTEMLIBS)
             optimized ${ARCH_PREBUILT_DIRS_RELEASE}/libxml2_a.lib
         )
     else()
-        set(LIBXML2_LIBRARIES xml2 iconv)
+        set(LIBXML2_LIBRARIES xml2)
     endif()
     set(LIBXML2_INCLUDE_DIRS ${LIBS_PREBUILT_DIR}/include/libxml2)
 endif(USESYSTEMLIBS)