delete not longer needed libvmaf modifications (homebrew-ffmpeg#117)

* delete not longer needed `libvmaf` modifications

* bump revision

Formula/ffmpeg.rb

@@ -5,6 +5,7 @@ class Ffmpeg < Formula
   version "5.1-with-options" # to distinguish from homebrew-core's ffmpeg
   sha256 "55eb6aab5ee235550fa54a33eaf8bf1b4ec66c01453182b12f6a993d75698b03"
   license "GPL-2.0-or-later"
+  revision 1
   head "https://github.com/FFmpeg/FFmpeg.git"
 
   option "with-chromaprint", "Enable the Chromaprint audio fingerprinting library"
@@ -190,15 +191,6 @@ def install
       args << "--enable-libopencore-amrwb"
     end
 
-    if build.with? "libvmaf"
-      # Replace hardcoded default VMAF model path
-      %w[doc/filters.texi libavfilter/vf_libvmaf.c].each do |f|
-        inreplace f, "/usr/local/share/model", HOMEBREW_PREFIX/"share/libvmaf/model"
-        # Since libvmaf v2.0.0, `.pkl` model files have been deprecated in favor of `.json` model files.
-        inreplace f, "vmaf_v0.6.1.pkl", "vmaf_v0.6.1.json"
-      end
-    end
-
     system "./configure", *args
     system "make", "install"