wmhdplop: Modernize autotools.

wmhdplop: Modernize autotools.

In particular, fix the following errors and warnings:

 configure.ac:2: warning: AM_INIT_AUTOMAKE: two- and three-arguments forms are
 deprecated.  For more info, see:
 configure.ac:2: http://www.gnu.org/software/automake/manual/automake.html
 #Modernize-AM_005fINIT_005fAUTOMAKE-invocation

 Makefile.am:21: error: linker flags such as '-shared' belong in
 'gkhdplop_so_LDFLAGS'

 ./configure: line 2910: syntax error near unexpected token `build_old_libs,'
 ./configure: line 2910: `    _LT_DECL(build_old_libs, enable_static, 0,'

 ./configure: line 2908: syntax error near unexpected token
 `build_libtool_libs,'
 ./configure: line 2908: `    _LT_DECL(build_libtool_libs, enable_shared, 0,

https://sources.debian.net/src/wmhdplop/0.9.9-5/debian/patches/
  modernize_autotools.patch/