Add CHECK_FOR_INTERRUPTS into pg_numa_query_pages

Querying the NUMA status can be quite time consuming, especially with
large shared buffers. 8cc139bec3 called numa_move_pages() once, for
all buffers, and we had to wait for the syscall to complete.

But with the chunking, introduced by 7fe2f67c7c to work around a kernel
bug, we can do CHECK_FOR_INTERRUPTS() after each chunk, allowing users
to abort the execution.

Reviewed-by: Christoph Berg <myon@debian.org>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aEtDozLmtZddARdB@msg.df7cb.de
Backpatch-through: 18

src/port/pg_numa.c

@@ -16,6 +16,7 @@
 #include "c.h"
 #include <unistd.h>
 
+#include "miscadmin.h"
 #include "port/pg_numa.h"
 
 /*
@@ -76,6 +77,8 @@ pg_numa_query_pages(int pid, unsigned long count, void **pages, int *status)
 		unsigned long count_chunk = Min(count - next,
 										NUMA_QUERY_CHUNK_SIZE);
 
+		CHECK_FOR_INTERRUPTS();
+
 		/*
 		 * Bail out if any of the chunks errors out (ret<0). We ignore
 		 * (ret>0) which is used to return number of nonmigrated pages,