shared/install: propagate all errors in install_info_apply()

Currently, install_info_apply() only updates r if it's 0,
meaning that if one of the earlier install_info_symlink_alias/wants()
calls returns > 0, errors generated by later calls will be discarded.
Fix that.

(cherry picked from commit a159aa07e1548367d2fde80cb0d45b869c591864)
(cherry picked from commit bb83650f96af1a7f803696fab5dd06442c789b1c)

src/shared/install.c

@@ -2105,15 +2105,15 @@ static int install_info_apply(
         r = install_info_symlink_alias(scope, info, lp, config_path, force, changes, n_changes);
 
         q = install_info_symlink_wants(scope, file_flags, info, lp, config_path, info->wanted_by, ".wants/", changes, n_changes);
-        if (r == 0)
+        if (q != 0 && r >= 0)
                 r = q;
 
         q = install_info_symlink_wants(scope, file_flags, info, lp, config_path, info->required_by, ".requires/", changes, n_changes);
-        if (r == 0)
+        if (q != 0 && r >= 0)
                 r = q;
 
         q = install_info_symlink_wants(scope, file_flags, info, lp, config_path, info->upheld_by, ".upholds/", changes, n_changes);
-        if (r == 0)
+        if (q != 0 && r >= 0)
                 r = q;
 
         return r;