[Stdlib] Move the declaration of __swift_ssize_t to SwiftStddef.h so Random.h/cpp can use it.

Author: mikeash

stdlib/public/SwiftShims/LibcShims.h

@@ -31,22 +31,6 @@
 namespace swift { extern "C" {
 #endif
 
-// This declaration is not universally correct.  We verify its correctness for
-// the current platform in the runtime code.
-#if defined(__linux__) && (defined(__arm__) || defined(__i386__))
-typedef           int __swift_ssize_t;
-#elif defined(_WIN32)
-#if defined(_M_ARM) || defined(_M_IX86)
-typedef           int __swift_ssize_t;
-#elif defined(_M_X64) || defined(_M_ARM64)
-typedef long long int __swift_ssize_t;
-#else
-#error unsupported machine type
-#endif
-#else
-typedef      long int __swift_ssize_t;
-#endif
-
 // This declaration might not be universally correct.
 // We verify its correctness for the current platform in the runtime code.
 #if defined(__linux__)

stdlib/public/SwiftShims/SwiftStddef.h

@@ -28,4 +28,20 @@ typedef size_t __swift_size_t;
 typedef __SIZE_TYPE__ __swift_size_t;
 #endif
 
+// This declaration is not universally correct.  We verify its correctness for
+// the current platform in the runtime code.
+#if defined(__linux__) && (defined(__arm__) || defined(__i386__))
+typedef           int __swift_ssize_t;
+#elif defined(_WIN32)
+#if defined(_M_ARM) || defined(_M_IX86)
+typedef           int __swift_ssize_t;
+#elif defined(_M_X64) || defined(_M_ARM64)
+typedef long long int __swift_ssize_t;
+#else
+#error unsupported machine type
+#endif
+#else
+typedef      long int __swift_ssize_t;
+#endif
+
 #endif // SWIFT_STDLIB_SHIMS_SWIFT_STDDEF_H