base: Add a warn_if macro
base: Add a warn_if macro

Add a warn if macro that is analogous to the panic_if and fatal_if.

vovojh/gem5,vovojh/gem5,pombredanne/http-repo.gem5.org-gem5-,pombredanne/http-repo.gem5.org-gem5-,pombredanne/http-repo.gem5.org-gem5-,vovojh/gem5,vovojh/gem5,pombredanne/http-repo.gem5.org-gem5-,vovojh/gem5,vovojh/gem5,pombredanne/http-repo.gem5.org-gem5-,pombredanne/http-repo.gem5.org-gem5-,vovojh/gem5,pombredanne/http-repo.gem5.org-gem5-