shadow: Remove -Werror=format-nonliteral from compiler flags

shadow uses non-literal format strings to integrate system information
into the login prompt. This is harmless because harmful format strings
are checked for (and in the worst case, the strings come from a file
that is writable by root only).

Removing -Werror=format-nonliteral here allows us to use
-Werror=format-nonliteral globally in OPTIMIZE_FOR=security mode
while keeping shadow building.

Signed-off-by: Bernhard Rosenkränzer <bernhard.rosenkraenzer.ext@huawei.com>

meta-ohos-core/recipes-extended/shadow/shadow_%.bbappend

+# SPDX-FileCopyrightText: Huawei Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+# shadow uses non-literal format strings to integrate system information
+# into the login prompt. This is harmless because harmful format strings
+# are checked for (and in the worst case, the strings come from a file
+# that is writable by root only).
+#
+# Removing -Werror=format-nonliteral here allows us to use
+# -Werror=format-nonliteral globally in OPTIMIZE_FOR=security mode
+# while keeping shadow building.
+
+TARGET_CFLAGS_remove = "-Werror=format-nonliteral"