target/arm: Introduce pc_curr

target/arm: Introduce pc_curr

Add a new field to retain the address of the instruction currently
being translated.  The 32-bit uses are all within subroutines used
by a32 and t32.  This will become less obvious when t16 support is
merged with a32+t32, and having a clear definition will help.

Convert aarch64 as well for consistency.  Note that there is one
instance of a pre-assert fprintf that used the wrong value for the
address of the current instruction.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190807045335.1361-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>