Support --with-lg-page values larger than system page size.

All mappings continue to be PAGE-aligned, even if the system page size
is smaller.  This change is primarily intended to provide a mechanism
for supporting multiple page sizes with the same binary; smaller page
sizes work better in conjunction with jemalloc's design.

This resolves #467.

src/jemalloc.c

@@ -1220,7 +1220,9 @@ malloc_init_hard_a0_locked() {
 			}
 		}
 	}
-	pages_boot();
+	if (pages_boot()) {
+		return true;
+	}
 	if (base_boot(TSDN_NULL)) {
 		return true;
 	}