add use-<proj>-custom FOO for any commit/branch/tag

While it was possible before to build any branch of mpv/ffmpeg/etc by
just git checkout $whatever and then ./build, it got reset after
./rebuild or ./update etc.

Add use-mpv-custom and use-ffmpeg-custom which accept any
commit/branch/tag which will survive ./rebuild, ./update, etc.

This should make it slightly easier to build past versions of mpv.

While at it, also add use-libass-{master|custom}

1 files changed, 9 insertions, 6 deletions

diff --git a/update b/update
index d966018..dfe16f8 100755
--- a/update
+++ b/update
@@ -65,21 +65,24 @@ do_fixedref()
     )
 }
 
-# args: $1: project name, $2: release/master [,$3: non-empty to ignore the config file]
+# args: $1: project name, $2: release/master/@foo [,$3: non-empty to ignore the config file]
 checkout()
 {
-    local arg="$2"
+    local branch="$2"
     if [ -z "$3" ] && [ -d config/ ] && [ -f config/branch-$1 ]; then
-        arg="$(cat config/branch-$1)"
+        branch="$(cat config/branch-$1)"
     fi
 
-    case "$arg" in
+    case "$branch" in
         master)  do_gitmaster $1;;
-        *)       do_releasetag $1;;
+        release) do_releasetag $1;;
+        @*)      do_fixedref $1 "${branch#@}";;  # everything after the '@' prefix
+        *)       >&2 printf "%s\n" "Error: Don't know how to checkout '$branch'"
+                 return 1
     esac
 }
 
-# fallback targets: release/master if no config file
+# fallback targets: release/master/@foo if no config file
 checkout_ffmpeg=master
 #checkout_fribidi=release
 checkout_libass=master