Use __typeof__() instead of typeof()

typeof() is a gcc builtin and is not always available (such as clang when
-std=c*). Both gcc and clang always expose __typeof__(), so just use that.

Change-Id: I75e2a990acc35f6f39b2c353f6548100ec03c67f

libc/include/unistd.h

@@ -207,7 +207,7 @@ extern int setdomainname(const char *, size_t);
 
 /* Used to retry syscalls that can return EINTR. */
 #define TEMP_FAILURE_RETRY(exp) ({         \
-    typeof (exp) _rc;                      \
+    __typeof__(exp) _rc;                   \
     do {                                   \
         _rc = (exp);                       \
     } while (_rc == -1 && errno == EINTR); \