15.6.5 AC_FOO_IFELSEÂÐAC_TRY_FOO

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AC_EGREP_CPP(yes,
[#ifdef _AIX
  yes
#endif
], is_aix=yes, is_aix=no)

¾åµ­¤ÎÎã¤Ç¤Ï¡¤Å¬Àڤ˽ñ¤«¤ì¤Æ¤¤¤ë(i)AC_LANG_PROGRAM¤ò»ÈÍѤ·¡¤(ii) ¥³¥ó¥Ñ¥¤¥é¤ò¼Â¹Ô¤¹¤Ù¤­¤Ç¤¹¡¥

AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
[[#if !defined _AIX
# error _AIX not defined
#endif
]])],
                   [is_aix=yes],
                   [is_aix=no])