Fix autoconf warnings


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1122 632fc199-4ca6-4c93-a231-07263d6284db
diff --git a/configure.ac b/configure.ac
index 6234641..01a2690 100644
--- a/configure.ac
+++ b/configure.ac
@@ -16,7 +16,9 @@
 SAVED_CPPFLAGS=${CPPFLAGS}
 AC_PROG_CPP
 AC_PROG_CC
+AM_PROG_AR
 AM_PROG_AS
+AM_PROG_CC_C_O
 AC_PROG_INSTALL
 AC_PROG_LIBTOOL
 AC_PROG_LN_S
@@ -235,13 +237,13 @@
   global: *;
 };
 EOF
-AC_LINK_IFELSE(AC_LANG_PROGRAM([], []),
+AC_LINK_IFELSE([AC_LANG_PROGRAM([], [])],
   [VERSION_SCRIPT_FLAG=-Wl,--version-script,;
    AC_MSG_RESULT([yes (GNU style)])],
   [])
 if test "x$VERSION_SCRIPT_FLAG" = "x"; then
   LDFLAGS="$SAVED_LDFLAGS -Wl,-M,conftest.map"
-  AC_LINK_IFELSE(AC_LANG_PROGRAM([], []),
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([], [])],
     [VERSION_SCRIPT_FLAG=-Wl,-M,;
      AC_MSG_RESULT([yes (Sun style)])],
     [])