Try to fix some DSA-related compiler warnings.

Commit 13df76a5 was overconfident
about how portable %016lx is.  Some compilers complain because they
need %016llx, while platforms where DSA pointers are only 32 bits
get unhappy about using a 64-bit format for a 32-bit quantity.

Thomas Munro, per an off-list suggestion from me.

src/backend/utils/mmgr/dsa.c

@@ -1099,9 +1099,10 @@ dsa_dump(dsa_area *area)
 
 						span = dsa_get_address(area, span_pointer);
 						fprintf(stderr,
-								"        span descriptor at %016lx, "
-								"superblock at %016lx, pages = %zu, "
-								"objects free = %hu/%hu\n",
+								"        span descriptor at "
+								DSA_POINTER_FORMAT ", superblock at "
+								DSA_POINTER_FORMAT
+								", pages = %zu, objects free = %hu/%hu\n",
 								span_pointer, span->start, span->npages,
 								span->nallocatable, span->nmax);
 						span_pointer = span->nextspan;

src/include/utils/dsa.h

@@ -54,6 +54,7 @@ typedef pg_atomic_uint32 dsa_pointer_atomic;
 #define dsa_pointer_atomic_write pg_atomic_write_u32
 #define dsa_pointer_atomic_fetch_add pg_atomic_fetch_add_u32
 #define dsa_pointer_atomic_compare_exchange pg_atomic_compare_exchange_u32
+#define DSA_POINTER_FORMAT "%08x"
 #else
 typedef uint64 dsa_pointer;
 typedef pg_atomic_uint64 dsa_pointer_atomic;
@@ -62,6 +63,7 @@ typedef pg_atomic_uint64 dsa_pointer_atomic;
 #define dsa_pointer_atomic_write pg_atomic_write_u64
 #define dsa_pointer_atomic_fetch_add pg_atomic_fetch_add_u64
 #define dsa_pointer_atomic_compare_exchange pg_atomic_compare_exchange_u64
+#define DSA_POINTER_FORMAT "%016" INT64_MODIFIER "x"
 #endif
 
 /* A sentinel value for dsa_pointer used to indicate failure to allocate. */