tools: Split the list of source plugins out of "merge-all-source-plugins"

(cherry picked from commit fd31df43067fe21cc1e4fabd07ee9d6a26cb7264)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

tools/merge-all-source-plugins

@@ -31,7 +31,16 @@ git diff --cached --exit-code >/dev/null ||\
 
 version="8.0"
 
-merge "https://github.com/michaelni/FFmpeg.git" "libpostproc"
+[ $# -ne 1 ] &&\
+    error "Usage: $0 source-plugins.txt"
+
+while IFS=' ' read -r a b; do
+    case "$a" in
+        ''|'#'*) continue ;;
+    esac
+
+    merge "$a" "$b"
+done < "$1"
 
 [ -n "$version"  ] && echo version: $version
 [ -n "$succeeded" ] && echo Succeeded merging: $succeeded

tools/source-plugins.txt

@@ -0,0 +1,4 @@
+# List of source plugins
+
+# libpostproc, GPL, maintained by Michael Niedermayer
+https://github.com/michaelni/FFmpeg.git libpostproc