libxl: explicitly check for libmath in autoconf

As well as explicitly add -lm to libxl's Makefile.

This is because next patch uses floating point arithmetic, and
it is better to state it clearly that we need libmath (just in
case we find a libc  that wants that to be explicitly enforced).

Notice that autoconf should be rerun after applying this change.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
[ ijc -- s/libmath/libm/ in error message ]
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/tools/configure b/tools/configure
index de0327c12b..2ac7e5cf76 100755
--- a/tools/configure
+++ b/tools/configure
@@ -6253,6 +6253,53 @@ else
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for isnan in -lm" >&5
+$as_echo_n "checking for isnan in -lm... " >&6; }
+if test "${ac_cv_lib_m_isnan+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lm  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char isnan ();
+int
+main ()
+{
+return isnan ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_m_isnan=yes
+else
+  ac_cv_lib_m_isnan=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_m_isnan" >&5
+$as_echo "$ac_cv_lib_m_isnan" >&6; }
+if test "x$ac_cv_lib_m_isnan" = x""yes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBM 1
+_ACEOF
+
+  LIBS="-lm $LIBS"
+
+else
+  as_fn_error $? "Could not find libm" "$LINENO" 5
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for MD5 in -lcrypto" >&5
 $as_echo_n "checking for MD5 in -lcrypto... " >&6; }
 if test "${ac_cv_lib_crypto_MD5+set}" = set; then :