busybox: allow build with musl

The musl C library does not yet implemented the getpwent_r() function,
needed by the Busybox password code when CONFIG_USE_BB_PWD_GRP is
disabled. So we enable it when the musl C library is used.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/busybox/busybox.mk

@@ -153,6 +153,15 @@ define BUSYBOX_INTERNAL_SHADOW_PASSWORDS
 endef
 endif
 
+# We also need to use internal functions when using the musl C
+# library, since some of them are not yet implemented by musl.
+ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y)
+define BUSYBOX_INTERNAL_SHADOW_PASSWORDS
+	$(call KCONFIG_ENABLE_OPT,CONFIG_USE_BB_PWD_GRP,$(BUSYBOX_BUILD_CONFIG))
+	$(call KCONFIG_ENABLE_OPT,CONFIG_USE_BB_SHADOW,$(BUSYBOX_BUILD_CONFIG))
+endef
+endif
+
 ifeq ($(BR2_INIT_BUSYBOX),y)
 define BUSYBOX_SET_INIT
 	$(call KCONFIG_ENABLE_OPT,CONFIG_INIT,$(BUSYBOX_BUILD_CONFIG))