qemu: disable use of signalfd system call

Otherwise it may crash on ARM devices with Android 8+.

packages/qemu-system-x86-64-headless/0016-disable-signalfd.patch

@@ -0,0 +1,15 @@
+diff -uNr qemu-6.1.0/meson.build qemu-6.1.0.mod/meson.build
+--- qemu-6.1.0/meson.build	2021-08-25 21:20:39.873631512 +0300
++++ qemu-6.1.0.mod/meson.build	2021-08-25 21:21:35.135670419 +0300
+@@ -1411,11 +1411,6 @@
+   #include <sys/mman.h>
+   #include <stddef.h>
+   int main(void) { return posix_madvise(NULL, 0, POSIX_MADV_DONTNEED); }'''))
+-config_host_data.set('CONFIG_SIGNALFD', cc.links(gnu_source_prefix + '''
+-  #include <unistd.h>
+-  #include <sys/syscall.h>
+-  #include <signal.h>
+-  int main(void) { return syscall(SYS_signalfd, -1, NULL, _NSIG / 8); }'''))
+ config_host_data.set('CONFIG_SPLICE', cc.links(gnu_source_prefix + '''
+   #include <unistd.h>
+   #include <fcntl.h>