memcached: add patch to fix error for debug build

Took me an annoyingly long time to find a mask that the ndk was happy
with. The original mask gives identical permissions as this one (and
several other variants I tried). printf("%d\n", ~(S_IRUSR | S_IWUSR));
returns a negative number, and I guess that is the reason the ndk is
unhappy.

Original error message:

restart.c:233:48: error: 'umask' called with invalid mode
    mode_t oldmask = umask(~(S_IRUSR | S_IWUSR));
                                               ^
/home/builder/.termux-build/_cache/android-r21d-api-24-v3/bin/../sysroot/usr/include/bits/fortify/stat.h:47:5: note: from 'diagnose_if' attribute on 'umask':
    __clang_error_if(mode & ~0777, "'umask' called with invalid mode") {
    ^                ~~~~~~~~~~~~
/home/builder/.termux-build/_cache/android-r21d-api-24-v3/bin/../sysroot/usr/include/sys/cdefs.h:134:52: note: expanded from macro '__clang_error_if'
                                                   ^
1 error generated.
make[2]: *** [Makefile:1060: memcached-restart.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [Makefile:1699: all-recursive] Error 1

packages/memcached/restart.c.patch

@@ -0,0 +1,11 @@
+--- ../restart.c.orig	2021-02-04 16:19:28.622976160 +0000
++++ ./restart.c	2021-02-04 17:49:12.448526739 +0000
+@@ -230,7 +230,7 @@
+ 
+     // restrictive permissions for the metadata file.
+     // TODO: also for the mmap file eh? :P
+-    mode_t oldmask = umask(~(S_IRUSR | S_IWUSR));
++    mode_t oldmask = umask(S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+     FILE *f = fopen(metafile, "w");
+     umask(oldmask);
+     if (f == NULL) {