linux-atm: Add missing headers

This fixes compilation with -Werror=implicit-function-declaration.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
(cherry picked from commit 1b1c47577bac99bdd8ab9ecde928ab0398f78799)

package/network/utils/linux-atm/Makefile

@@ -10,7 +10,7 @@ include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=linux-atm
 PKG_VERSION:=2.5.2
-PKG_RELEASE:=6
+PKG_RELEASE:=7
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@SF/$(PKG_NAME)

package/network/utils/linux-atm/patches/700-musl-include.patch

@@ -0,0 +1,30 @@
+--- a/src/include/atmd.h
++++ b/src/include/atmd.h
+@@ -10,6 +10,7 @@
+ 
+ #include <stdint.h>
+ #include <stdio.h>
++#include <string.h>
+ #include <sys/types.h>
+ #include <sys/time.h>
+ 
+--- a/src/lib/unix.c
++++ b/src/lib/unix.c
+@@ -8,6 +8,7 @@
+ 
+ #include <stdlib.h>
+ #include <stdio.h>
++#include <string.h>
+ #include <unistd.h>
+ #include <errno.h>
+ #include <sys/types.h>
+--- a/src/sigd/kernel.c
++++ b/src/sigd/kernel.c
+@@ -8,6 +8,7 @@
+ 
+ #include <stdlib.h>
+ #include <stdio.h>
++#include <string.h>
+ #include <errno.h>
+ #include <assert.h>
+