Don't intercept Escape key while IME is active.

Don't intercept Escape key while IME is active.

Escape is used by IME and intercepting it at wxWidgets level to generate
EVT_CHAR_HOOK breaks the IME UI and may result in unexpected loss of data
entered by user.

To work around this, don't generate EVT_CHAR_HOOK for Escape while IME is
active by checking for the special semaphore variable (which could be also
used for other things in the future, see #9102) value.

Closes #11386.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67189 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775