fix 'autoconf -Wall' warning

[Ralf Wildenhues]

Applied to HEAD as obvious, autoconf warns about it with -Wall.  The
AC_MSG_* have been escaping since Autoconf 2.53 or so, and we require
2.58 anyway.

Cheers,
Ralf

2008-03-17  Ralf Wildenhues  <address@hidden>

        * libltdl/m4/libtool.m4 (_LT_CHECK_BUILDDIR): No need to escape
        backticks in argument to AC_MSG_WARN or AC_MSG_ERROR.
        * libltdl/m4/ltdl.m4 (_LTDL_INSTALLABLE, LTDL_INIT): Likewise.

Index: libltdl/m4/libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/m4/libtool.m4,v
retrieving revision 1.143
diff -u -r1.143 libtool.m4
--- libltdl/m4/libtool.m4       12 Mar 2008 19:48:24 -0000      1.143
+++ libltdl/m4/libtool.m4       17 Mar 2008 22:37:52 -0000
@@ -57,7 +57,7 @@
 m4_defun([_LT_CHECK_BUILDDIR],
 [case `pwd` in
   *\ * | *\    *)
-    AC_MSG_WARN([Libtool does not cope well with whitespace in \`pwd\`]) ;;
+    AC_MSG_WARN([Libtool does not cope well with whitespace in `pwd`]) ;;
 esac
 ])
 
Index: libltdl/m4/ltdl.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/m4/ltdl.m4,v
retrieving revision 1.44
diff -u -r1.44 ltdl.m4
--- libltdl/m4/ltdl.m4  12 Mar 2008 19:48:25 -0000      1.44
+++ libltdl/m4/ltdl.m4  17 Mar 2008 22:37:53 -0000
@@ -154,7 +154,7 @@
   if test x"${lt_lib_ltdl-no}" = xyes; then
     if test x"$enable_ltdl_install" != xyes; then
       # Don't overwrite $prefix/lib/libltdl.la without --enable-ltdl-install
-      AC_MSG_WARN([not overwriting libltdl at $prefix, force with 
\`--enable-ltdl-install'])
+      AC_MSG_WARN([not overwriting libltdl at $prefix, force with 
`--enable-ltdl-install'])
       enable_ltdl_install=no
     fi
   elif test x"$enable_ltdl_install" = xno; then
@@ -287,7 +287,7 @@
 if test -n "$with_ltdl_include"; then
   if test -f "$with_ltdl_include/ltdl.h"; then :
   else
-    AC_MSG_ERROR([invalid ltdl include directory: \`$with_ltdl_include'])
+    AC_MSG_ERROR([invalid ltdl include directory: `$with_ltdl_include'])
   fi
 else
   with_ltdl_include=no
@@ -300,7 +300,7 @@
 if test -n "$with_ltdl_lib"; then
   if test -f "$with_ltdl_lib/libltdl.la"; then :
   else
-    AC_MSG_ERROR([invalid ltdl library directory: \`$with_ltdl_lib'])
+    AC_MSG_ERROR([invalid ltdl library directory: `$with_ltdl_lib'])
   fi
 else
   with_ltdl_lib=no
@@ -323,7 +323,7 @@
        LTDLINCL=
        ;;
   ,no*,no,*)
-       AC_MSG_ERROR([\`--with-ltdl-include' and \`--with-ltdl-lib' options 
must be used together])
+       AC_MSG_ERROR([`--with-ltdl-include' and `--with-ltdl-lib' options must 
be used together])
        ;;
   *)   with_included_ltdl=no
        LIBLTDL="-L$with_ltdl_lib -lltdl"