[wasm][stdlib] Stop including stdint.h in wasi-libc for SwiftShims

To avoid `error: 'stddef.h' file not found' issue described in
SwiftStdint.h

Author: kateinoigakukun

stdlib/public/SwiftShims/swift/shims/SwiftStdint.h

@@ -24,7 +24,7 @@
 
 // Clang has been defining __INTxx_TYPE__ macros for a long time.
 // __UINTxx_TYPE__ are defined only since Clang 3.5.
-#if !defined(__APPLE__) && !defined(__linux__) && !defined(__OpenBSD__)
+#if !defined(__APPLE__) && !defined(__linux__) && !defined(__OpenBSD__) && !defined(__wasi__)
 #include <stdint.h>
 typedef int64_t __swift_int64_t;
 typedef uint64_t __swift_uint64_t;