Hexagon (target/hexagon) probe the stores in a packet at start of commit

When a packet has 2 stores, either both commit or neither commit.
At the beginning of gen_commit_packet, we check for multiple stores.
If there are multiple stores, call a helper that will probe each of
them before proceeding with the commit.

Note that we don't call the probe helper for packets with only one
store.  Therefore, we call process_store_log before anything else
involved in committing the packet.

We also fix a typo in the comment in process_store_log.

Test case added in tests/tcg/hexagon/hex_sigsegv.c

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <1633036599-7637-1-git-send-email-tsimpson@quicinc.com>