abuild: normalize path when finding symlink targets

some paths like usr/lib/../../lib/libudev.so.0.13.0 will fail to resolve
if usr/lib is does not exist, even if lib/libudev.so.0.13.0 does.

To solve thise we normalize out the ../ in path string before we try to
resolve it.

abuild.in

@@ -1180,6 +1180,21 @@ scan_shared_objects() {
 	done > "$controldir"/.needs-so
 }
 
+# normalize a path string
+normalize_path() {
+	local oifs="$IFS" pathstr= i=
+	IFS='/'
+	set -- $1
+	for i; do
+		case "$i" in
+		"."|"") continue;;
+		"..")   pathstr="${pathstr%%/${pathstr##*/}}";;
+		*) pathstr="${pathstr}/$i";;
+		esac
+	done
+	echo "$pathstr"
+}
+
 # find which package provides file that symlink points to
 scan_symlink_targets() {
 	local name="$1" dir="$2" datadir="$3"
@@ -1188,10 +1203,10 @@ scan_symlink_targets() {
 	for symfile in "$pkgbasedir"/.control.*/.symlinks; do
 		[ -e "$symfile" ] || continue
 		while read symlink target; do
-			case "$target" in
-			/*) targetpath="${datadir}/$target";;
-			*) targetpath="${symlink%/*}/$target";;
-			esac
+			if [ "${target#/}" = "$target" ]; then
+				target="${symlink%/*}/$target"
+			fi
+			targetpath="$datadir"/$(normalize_path "$target")
 			if [ -e "$targetpath" ] || [ -L "$targetpath" ]; then
 				local d="${symfile%/.symlinks}"
 				echo "$name=$pkgver-r$pkgrel" \