Fix libtomcrypt/libtommath linking order

To prevent build failures when using system libtom libraries and
linking with --as-needed, LIBTOM_LIBS should be in the order
-ltomcrypt -ltommath, not the other way around, ie libs should be
prepended to LIBTOM_LIBS as they are found, not appended.

Signed-off-by: Andre McCurdy <armccurdy@gmail.com>

configure.ac

@@ -388,16 +388,16 @@ AC_ARG_ENABLE(bundled-libtom,
 			AC_MSG_NOTICE(Forcing bundled libtom*)
 		else
 			BUNDLED_LIBTOM=0
-			AC_CHECK_LIB(tommath, mp_exptmod, LIBTOM_LIBS="$LIBTOM_LIBS -ltommath", 
+			AC_CHECK_LIB(tommath, mp_exptmod, LIBTOM_LIBS="-ltommath $LIBTOM_LIBS",
 				[AC_MSG_ERROR([Missing system libtommath and --disable-bundled-libtom was specified])] )
-			AC_CHECK_LIB(tomcrypt, register_cipher, LIBTOM_LIBS="$LIBTOM_LIBS -ltomcrypt", 
+			AC_CHECK_LIB(tomcrypt, register_cipher, LIBTOM_LIBS="-ltomcrypt $LIBTOM_LIBS",
 				[AC_MSG_ERROR([Missing system libtomcrypt and --disable-bundled-libtom was specified])] )
 		fi
 	],
 	[
 		BUNDLED_LIBTOM=0
-		AC_CHECK_LIB(tommath, mp_exptmod, LIBTOM_LIBS="$LIBTOM_LIBS -ltommath", BUNDLED_LIBTOM=1)
-		AC_CHECK_LIB(tomcrypt, register_cipher, LIBTOM_LIBS="$LIBTOM_LIBS -ltomcrypt", BUNDLED_LIBTOM=1)
+		AC_CHECK_LIB(tommath, mp_exptmod, LIBTOM_LIBS="-ltommath $LIBTOM_LIBS", BUNDLED_LIBTOM=1)
+		AC_CHECK_LIB(tomcrypt, register_cipher, LIBTOM_LIBS="-ltomcrypt $LIBTOM_LIBS", BUNDLED_LIBTOM=1)
 	]
 )