memcached: fix musl build

- thx to alpinelinux for the patch
   (http://git.alpinelinux.org/cgit/aports/plain/main/memcached/musl-includes.patch)
 - remove depency to libenvent and replace it libevent2
   should fix issue #1542

Signed-off-by: heil <heil@terminal-consulting.de>

net/memcached/Makefile

@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=memcached
 PKG_VERSION:=1.4.24
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://memcached.org/files
@@ -24,7 +24,7 @@ include $(INCLUDE_DIR)/package.mk
 define Package/memcached
   SECTION:=net
   CATEGORY:=Network
-  DEPENDS:=+libevent +libpthread
+  DEPENDS:=+libevent2 +libpthread
   TITLE:=The high-performance, distributed memory object caching system
   URL:=http://memcached.org/
 endef

net/memcached/patches/001-musl-compat.patch

@@ -0,0 +1,47 @@
+--- memcached-1.4.15.orig/assoc.c
++++ memcached-1.4.15/assoc.c
+@@ -14,8 +14,8 @@
+ #include "memcached.h"
+ #include <sys/stat.h>
+ #include <sys/socket.h>
+-#include <sys/signal.h>
+ #include <sys/resource.h>
++#include <signal.h>
+ #include <fcntl.h>
+ #include <netinet/in.h>
+ #include <errno.h>
+--- memcached-1.4.15.orig/items.c
++++ memcached-1.4.15/items.c
+@@ -2,13 +2,13 @@
+ #include "memcached.h"
+ #include <sys/stat.h>
+ #include <sys/socket.h>
+-#include <sys/signal.h>
+ #include <sys/resource.h>
+ #include <fcntl.h>
+ #include <netinet/in.h>
+ #include <errno.h>
+ #include <stdlib.h>
+ #include <stdio.h>
++#include <signal.h>
+ #include <string.h>
+ #include <time.h>
+ #include <assert.h>
+--- memcached-1.4.15.orig/slabs.c
++++ memcached-1.4.15/slabs.c
+@@ -10,7 +10,6 @@
+ #include "memcached.h"
+ #include <sys/stat.h>
+ #include <sys/socket.h>
+-#include <sys/signal.h>
+ #include <sys/resource.h>
+ #include <fcntl.h>
+ #include <netinet/in.h>
+@@ -18,6 +17,7 @@
+ #include <stdlib.h>
+ #include <stdio.h>
+ #include <string.h>
++#include <signal.h>
+ #include <assert.h>
+ #include <pthread.h>
+