Copied the NO_UNDEFINED magic from libcurl to make this build fine again with

libtool cross-compiled on linux with mingw32

ares/Makefile.am

@@ -43,7 +43,13 @@ VER=-version-info 1:0:0
 # set age to 0. (c:r:a=0)
 #
 
-libcares_la_LDFLAGS = $(VER)
+if NO_UNDEFINED
+# The -no-undefined flag is crucial for this to build fine on some platforms
+UNDEF = -no-undefined
+endif
+
+
+libcares_la_LDFLAGS = $(UNDEF) $(VER)
 
 # Makefile.inc provides the CSOURCES and HHEADERS defines
 include Makefile.inc

ares/configure.ac

@@ -69,6 +69,18 @@ dnl libtool setup
 CARES_CLEAR_LIBTOOL_TAGS
 AC_PROG_LIBTOOL
 
+AC_MSG_CHECKING([if we need -no-undefined])
+case $host in
+  *-*-cygwin | *-*-mingw* | *-*-pw32*)
+    need_no_undefined=yes
+    ;;
+  *)
+    need_no_undefined=no
+    ;;
+esac
+AC_MSG_RESULT($need_no_undefined)
+AM_CONDITIONAL(NO_UNDEFINED, test x$need_no_undefined = xyes)
+
 dnl Checks for header files.
 AC_HEADER_STDC