Adapt to backwards incompatible change in GNU Make 4.3

GNU Make 4.3 has a backwards incompatible change affecting the use of
number signs or hashes (ie., #) inside function invocations. See:
https://lists.gnu.org/archive/html/info-gnu/2020-01/msg00004.html

In this case, it would expand the '\#' in the '\n\#include \"$(h)\"'
argument to the foreach call to '\#', not '#'. This would lead to
spurious backslashes in front of the '#include' directives in the
generated gstmpegts-enumtypes.c file.

Spotted by Ernestas Kulik.

https://gitlab.freedesktop.org/gstreamer/common/-/merge_requests/4
https://bugzilla.redhat.com/show_bug.cgi?id=1799497

gstreamer1-plugins-bad-build-adapt-to-backwards-incompatible-change.patch

@@ -0,0 +1,13 @@
+diff -urNp gst-plugins-bad-1.16.2.orig/common/gst-glib-gen.mak gst-plugins-bad-1.16.2/common/gst-glib-gen.mak
+--- gst-plugins-bad-1.16.2.orig/common/gst-glib-gen.mak	2020-03-20 14:57:08.587740695 +0100
++++ gst-plugins-bad-1.16.2/common/gst-glib-gen.mak	2020-03-20 15:00:42.584798988 +0100
+@@ -8,7 +8,8 @@
+ #glib_gen_decl_banner=GST_EXPORT
+ #glib_gen_decl_include=\#include <gst/foo/foo-prelude.h>
+ 
+-enum_headers=$(foreach h,$(glib_enum_headers),\n\#include \"$(h)\")
++hash:=\#
++enum_headers=$(foreach h,$(glib_enum_headers),\n$(hash)include \"$(h)\")
+ 
+ # these are all the rules generating the relevant files
+ $(glib_gen_basename)-marshal.h: $(glib_gen_basename)-marshal.list

gstreamer1-plugins-bad-free.spec

@@ -31,9 +31,15 @@ URL:            http://gstreamer.freedesktop.org/
 Source0:        gst-plugins-bad-free-%{version}.tar.xz
 Source1:        gst-p-bad-cleanup.sh
 
+# https://gitlab.freedesktop.org/gstreamer/common/-/merge_requests/4
+# https://bugzilla.redhat.com/show_bug.cgi?id=1799497
+Patch0:         gstreamer1-plugins-bad-build-adapt-to-backwards-incompatible-change.patch
+
 BuildRequires:  gstreamer1-devel >= %{version}
 BuildRequires:  gstreamer1-plugins-base-devel >= %{version}
 
+BuildRequires:  autoconf
+BuildRequires:  automake
 BuildRequires:  check
 BuildRequires:  gettext-devel
 BuildRequires:  libXt-devel
@@ -189,9 +195,11 @@ aren't tested well enough, or the code is not of good enough quality.
 
 %prep
 %setup -q -n gst-plugins-bad-%{version}
+%patch0 -p1
 
 
 %build
+autoreconf --force --install
 %configure --disable-silent-rules --disable-fatal-warnings \
     --with-package-name="Fedora GStreamer-plugins-bad package" \
     --with-package-origin="http://download.fedoraproject.org" \