imap-send: simplify v_issue_imap_cmd() and get_cmd_result() using starts_with()
imap-send: simplify v_issue_imap_cmd() and get_cmd_result() using starts_with()

Use starts_with() instead of memcmp() to check if NUL-terminated
strings match prefixes.  This gets rid of some magic string length
constants.

Signed-off-by: Rene Scharfe <2da278a99b557fc93ddbed7517a413ad793e2e6a@web.de>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git