Fix TEMP_FAILURE_RETRY on non-GNU C++ dialects

TEMP_FAILURE_RETRY uses typeof which is only allowed by gcc and clang
for GNU dialects. This switches to __typeof__ which is always supported.

Bug: 224644083
Test: m
Change-Id: I96d48d2f0dc5cd9ab903755d93c71c4eb80f7529

libutils/include/utils/Compat.h

@@ -71,19 +71,17 @@ static inline int ftruncate64(int fd, off64_t length) {
 #define CONSTEXPR
 #endif
 
-/*
- * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
- * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
- * not already defined, then define it here.
- */
+/* TEMP_FAILURE_RETRY is not available on macOS, but still useful there. */
 #ifndef TEMP_FAILURE_RETRY
 /* Used to retry syscalls that can return EINTR. */
-#define TEMP_FAILURE_RETRY(exp) ({         \
-    typeof (exp) _rc;                      \
-    do {                                   \
-        _rc = (exp);                       \
-    } while (_rc == -1 && errno == EINTR); \
-    _rc; })
+#define TEMP_FAILURE_RETRY(exp)                \
+    ({                                         \
+        __typeof__(exp) _rc;                   \
+        do {                                   \
+            _rc = (exp);                       \
+        } while (_rc == -1 && errno == EINTR); \
+        _rc;                                   \
+    })
 #endif
 
 #if defined(_WIN32)