rename sha1_* to mysql_sha1_*


include/sha1.h:
  rename sha1_* to mysql_sha1_*
mysys/sha1.c:
  rename sha1_* to mysql_sha1_*
sql/item_strfunc.cc:
  rename sha1_* to mysql_sha1_*
sql/password.c:
  rename sha1_* to mysql_sha1_*