Prevent virtual memory OOM in spectest fuzzing (#4872)

This commit hard-codes the pooling allocator's limit of linear memories
to 1 when used with fuzzing the spec tests themselves. This prevents the
number from being set too high and hitting a virtual-memory-based OOM
due to the virtual memory reservation of the pooling allocator being too
large.

crates/fuzzing/src/generators/config.rs

@@ -131,7 +131,7 @@ impl Config {
             // required to actually run the spec tests. Fuzz-generated inputs
             // may have limits less than these thresholds which would cause the
             // spec tests to fail which isn't particularly interesting.
-            limits.memories = limits.memories.max(1);
+            limits.memories = 1;
             limits.tables = limits.memories.max(5);
             limits.table_elements = limits.memories.max(1_000);
             limits.memory_pages = limits.memory_pages.max(900);