Revert "Change symlink_forest to use relative symlinks."

Revert submission 2673616-relativesymlinks-fix

Reason for revert: this breaks tests verified with go/abtd https://android-build.googleplex.com/builds/abtd/run/L36000000963001181

Bug: 300122962

Reverted changes: /q/submissionid:2673616-relativesymlinks-fix

Change-Id: I5a97c4fbe4df5727c0604a07137093d0f00c7776
diff --git a/bp2build/symlink_forest.go b/bp2build/symlink_forest.go
index a0c7e4c..5c33308 100644
--- a/bp2build/symlink_forest.go
+++ b/bp2build/symlink_forest.go
@@ -190,20 +190,10 @@
 
 // Creates a symbolic link at dst pointing to src
 func symlinkIntoForest(topdir, dst, src string) uint64 {
-	// b/259191764 - Make all symlinks relative
-	dst = shared.JoinPath(topdir, dst)
-	src = shared.JoinPath(topdir, src)
-	basePath := filepath.Dir(dst)
-	var dstPath string
-	srcPath, err := filepath.Rel(basePath, src)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Failed to find relative path for symlinking: %s\n", err)
-		os.Exit(1)
-	} else {
-		dstPath = dst
-	}
+	srcPath := shared.JoinPath(topdir, src)
+	dstPath := shared.JoinPath(topdir, dst)
 
-	// Check whether a symlink already exists.
+	// Check if a symlink already exists.
 	if dstInfo, err := os.Lstat(dstPath); err != nil {
 		if !os.IsNotExist(err) {
 			fmt.Fprintf(os.Stderr, "Failed to lstat '%s': %s", dst, err)