gdbstub: Introduce gdb_get_float32() to get 32-bit float registers

gdbstub: Introduce gdb_get_float32() to get 32-bit float registers

Since we now use a GByteArray, we can not use stfl_p() directly.
Introduce the gdb_get_float32() helper to load a float32 register.

Fixes: a010bdbe719 ("extend GByteArray to read register helpers")
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200414163853.12164-2-philmd@redhat.com>
Message-Id: <20200414200631.12799-14-alex.bennee@linaro.org>