Fixed error in test that caused following tests to fail

extra/yassl/taocrypt/src/dsa.cpp:
  Fixed compiler warning by adding cast
mysql-test/suite/rpl/t/rpl_start_slave_deadlock_sys_vars.test:
  We have to first test for have_debug_sync to not start master wrongly
plugin/auth_pam/auth_pam.c:
  Fixed compiler warning
sql/sys_vars.h:
  Fixed compiler warning (Sys_var_max_user_conn is now signed)
support-files/compiler_warnings.supp:
  Don't give warnings for auth_pam.c (Tried to fix it by changing the code, but could not find an easy way to do that on solaris)