abuild: exclude non-dangling symlinks from dependency resolution

This commit also fixes incorrect behavior in case where an absolute
symlink points to a file installed on the build host but which is
missing from the package.

abuild.in

@@ -886,13 +886,14 @@ prepare_trace_rpaths() {
 
 # search for broken symlinks so we later can pull in proper depends
 prepare_symlinks() {
+	local target
 	local dir="${subpkgdir:-$pkgdir}"
 	options_has "!tracedeps" && return 0
 	cd "$dir" || return 1
 	find -type l | while read symlink; do
-		if ! [ -e "$symlink" ]; then
-			echo "$symlink $(readlink $symlink)" \
-				>> "$controldir"/.symlinks
+		target=$(readlink "$symlink")
+		if ! [ -e "$dir$(normalize_target_path "$target" "$symlink")" ]; then
+			echo "$symlink $target" >> "$controldir"/.symlinks
 		fi
 	done
 }
@@ -1190,11 +1191,16 @@ scan_shared_objects() {
 	done > "$controldir"/.needs-so
 }
 
-# normalize a path string
-normalize_path() {
+# normalize a symlink target path (1st arg)
+# Converts a relative path to absolute with respect to the symlink
+# path (2nd arg).
+normalize_target_path() {
+	local path=$1
+	[ "${path:0:1}" = / ] || path=$(dirname "$2")/$path
+
 	local oifs="$IFS" pathstr= i=
 	IFS='/'
-	set -- $1
+	set -- $path
 	for i; do
 		case "$i" in
 		"."|"") continue;;
@@ -1217,10 +1223,7 @@ scan_symlink_targets() {
 		fi
 
 		while read symlink target; do
-			if [ "${target#/}" = "$target" ]; then
-				target="${symlink%/*}/$target"
-			fi
-			targetpath="$datadir"/$(normalize_path "$target")
+			targetpath=$datadir$(normalize_target_path "$target" "$symlink")
 			if [ -e "$targetpath" ] || [ -L "$targetpath" ]; then
 				echo "$name=$pkgver-r$pkgrel" \
 					>> "$d"/.symlinks-needs