pkg, db: use 's' for source repository tags instead of 'p'

Will use 'p' for provides.

src/database.c

@@ -776,6 +776,7 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
 			ipkg->replaces_priority = apk_blob_pull_uint(&l, 10);
 			break;
 		case 'p':
+		case 's':
 			ipkg->repository_tag = apk_db_get_tag_id(db, l);
 			break;
 		default:
@@ -825,7 +826,7 @@ static int apk_db_write_fdb(struct apk_database *db, struct apk_ostream *os)
 			apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
 		}
 		if (ipkg->repository_tag) {
-			apk_blob_push_blob(&bbuf, APK_BLOB_STR("p:"));
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR("s:"));
 			apk_blob_push_blob(&bbuf, *db->repo_tags[ipkg->repository_tag].name);
 			apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
 		}

src/package.c

@@ -748,7 +748,7 @@ int apk_pkg_add_info(struct apk_database *db, struct apk_package *pkg,
 		pkg->commit = apk_blob_cstr(value);
 		break;
 	case 'F': case 'M': case 'R': case 'Z': case 'r': case 'q':
-	case 'a': case 'p':
+	case 'a': case 'p': case 's':
 		/* installed db entries which are handled in database.c */
 		return 1;
 	default:

test/pinning.installed

@@ -4,7 +4,7 @@ V:3
 S:1
 I:1
 D:b
-p:testing
+s:testing
 
 C:Q1hdUpqRv5mYgJEqW52UmVsv23ysE=
 P:b
@@ -18,5 +18,5 @@ V:3
 S:1
 I:1
 D:a>=3
-p:testing
+s:testing