[Re-sending in plain text-mode, sorry for the duplicates]

Hi,

In PR91749, we have ICEs because -mflip-thumb switches to Thumb-1 (the
default target cpu does not support Thumb-2).

Although we already filter this in arm_configure_build_target, we
forgot to handle cases when the mode is changed via attributes (either
in the source code, or via -mflip-thumb).

This patch adds the same error message when trying to apply the
"thumb" attribute and the target does not support Thumb-2 (only if we
are in FDPIC mode, of course).

OK?

Thanks,

Christophe