exec: Fix overlap of PAGE_ANON and PAGE_TARGET_1

exec: Fix overlap of PAGE_ANON and PAGE_TARGET_1

Unfortuately, the elements of PAGE_* were not in numerical
order and so PAGE_ANON was added to an "unused" bit.
As an arbitrary choice, move PAGE_TARGET_{1,2} together.

Cc: Laurent Vivier <laurent@vivier.eu>
Fixes: 26bab757d41b ("linux-user: Introduce PAGE_ANON")
Buglink: https://bugs.launchpad.net/bugs/1922617
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Tested-by: Laurent Vivier <laurent@vivier.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>