Disable Fortran checks, thanks Greg! For whatever reason I only looked at the...

Disable Fortran checks, thanks Greg!  For whatever reason I only looked at the autoconf source, sigh.

Originally committed to SVN as r3101.

aegisub/configure.in

@@ -185,6 +185,7 @@ CHECK_GNU_MAKE
 AC_PROG_CC
 AC_PROG_CXX
 AC_LANG(C++)
+define([AC_LIBTOOL_LANG_F77_CONFIG], [:])
 AC_PROG_LIBTOOL
 AC_PROG_INSTALL
 PKG_PROG_PKG_CONFIG([pkgconfig_required_version])