Set SWIFT_ABI_WASM32_LEAST_VALID_POINTER to 4096

Author: MaxDesiatov

stdlib/public/SwiftShims/System.h

@@ -213,6 +213,6 @@
 // the pointer representation, runtime performance and memory footprint are
 // worse. So assume that compiler driver uses wasm-ld and --global-base=1024 to
 // reserve low 1KB.
-#define SWIFT_ABI_WASM32_LEAST_VALID_POINTER 1024
+#define SWIFT_ABI_WASM32_LEAST_VALID_POINTER 4096
 
 #endif // SWIFT_STDLIB_SHIMS_ABI_SYSTEM_H