Fix libatomic detection on ppc64

Thanks @tjikkun!

Closes #5456

(cherry picked from commit b16f46605d86a62e4f37bc1e2caab0c52fa9f75c)

diff --git a/m4/pdns_check_os.m4 b/m4/pdns_check_os.m4
index 2afdbb6bd4c5badc77edeca04aa52844008ba3fd..9ff7b1b054cb62d463271935ac9eb7572bc0e583 100644 (file)
--- a/m4/pdns_check_os.m4
+++ b/m4/pdns_check_os.m4
@@ -36,10 +36,12 @@ AC_DEFUN([PDNS_CHECK_OS],[
   AM_CONDITIONAL([HAVE_SOLARIS], [test "x$have_solaris" = "xyes"])
 
   case "$host" in
-  mips* | powerpc* )
-    AX_CHECK_LINK_FLAG([-latomic],
-      [ : ],
-      [ AC_MSG_ERROR([Unable to link against libatomic, cannot continue]) ]
+  mips* | powerpc-* )
+    AC_MSG_CHECKING([whether the linker accepts -latomic])
+    LDFLAGS="-latomic $LDFLAGS"
+    AC_LINK_IFELSE([m4_default([],[AC_LANG_PROGRAM()])],
+      [AC_MSG_RESULT([yes])],
+      [AC_MSG_ERROR([Unable to link against libatomic, cannot continue])]
     )
     LDFLAGS="-latomic $LDFLAGS"
     ;;